The inventor of Kevlar, the lightweight fibre used in bulletproof vests and body armour, has died aged 90.
Stephanie Kwolek was a chemist at the DuPont company in Wilmington, Delaware, when she invented the stronger-than-steel fibre in 1965.
It was initially intended to be used in automobile tyres.
In a statement, DuPont chief executive Ellen Kullman described Kwolek as "a creative and determined chemist and a true pioneer for women in science".
Kwolek is the only female employee of DuPont to be awarded the company's Lavoisier Medal for outstanding technical achievement.
"I knew that I had made a discovery," Kwolek said in an interview several years ago. "I didn't shout 'Eureka,' but I was very excited, as was the whole laboratory excited, and management was excited because we were looking for something new, something different, and this was it."
She retired from the company in 1986.
Since the invention of Kevlar, the material has saved thousands of lives, including that of Police Lt David Spicer, who while recovering from his wounds in 2001, spoke to Kwolek on the phone.
"She was a tremendous woman," Lt Spicer told the Associated Press news agency.
Aside from protective clothing, the fibre is found in a variety of products, including aeroplanes, mobile phones, and sailboats.
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Shia cleric Moqtada al-Sadr has rallied followers to join a military parade across Iraq, as Jonathan Beale reports from Baghdad
Thousands of Shia militia loyal to the powerful cleric Moqtada al-Sadr have paraded through the streets of Baghdad, raising sectarian tensions amid continued fighting in areas of Iraq.
The cleric, whose Mehdi Army fought the US in Iraq for years, had called for a military parade across the country.
Correspondents say the show of force will be seen as a very disturbing development by the Baghdad government.
Sunni extremists have seized control of large swathes of territory across Iraq.
On Saturday, the militants - led by jihadist group Isis - were reported to have seized a strategically important border crossing to Syria, near the town of Qaim, killing 30 troops after a day-long battle.
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Fergal Keane reports: ''Isis suspects surrender (to the Kurdish snipers) and are made to strip for fear they are wearing suicide vests''
Thousands of largely Shia Iraqis have volunteered to fight Isis, urged on by a call from the country's highest Shia religious authority, Grand Ayatollah Ali al-Sistani.
But the BBC's Jim Muir, in northern Iraq, says the impressive-looking parade of men in battle fatigues accompanied by serious military hardware will only raise sectarian tensions at at time when the government is under pressure to rally the country together against the extremists.
Iraq's sectarian split
Sunnis and Shia share fundamental beliefs, but differ in doctrine, ritual, law, theology and religious organisation
The origins of the split lie in a dispute over who should have succeeded the Prophet Muhammad as leader of the Muslim community
Sunnis are the majority sect in the Muslim world, but Shia, most of them ethnic Arabs, form between 60% and 65% of Iraq's population; Sunnis make up 32-37%, split between Arabs and Kurds
Sunni Arabs dominated Iraq under Saddam Hussein and their persecution of the Shia stoked sectarian tensions; the US-led invasion in 2003 gave the Shia an opportunity to seek redress
Nouri Maliki has been accused of denying Sunni Arabs meaningful representation and pursuing security policies that target them
US Secretary of State John Kerry is expected to travel to Iraq soon to press for a more representative cabinet, hoping this could ease tensions between the country's rival Muslim sects.
Meanwhile, US President Barack Obama said Isis - which has an estimated 10,000 fighters in Iraq and Syria - had exploited a power vacuum in Syria to amass arms and resources, but denied this was because the US had not moved to back moderate rebel forces fighting President Bashar Assad.
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Obama dismisses notion of "ready-made moderate Syrian force able to defeat Assad"
"We have spent a lot of time trying to work with a moderate opposition in Syria, but... when you get farmers and dentists and folks who have never fought before going up against a ruthless opposition in Assad, the notion that they were in a position suddenly to overturn not only Assad but also ruthless, highly-trained jihadists if we just sent a few arms is a fantasy," he told CBS News.
The US, which pulled out of Iraq in 2011, is sending some 300 military advisers to Iraq to help in the fight against the insurgents there.
But in the face of Iraqi calls for US air strikes, the White House is insisting that there is no purely military solution to the crisis.
The BBC's John Simpson, in Baghdad, says Mr Obama believes Iraqi PM Nouri Maliki has endangered the country by ignoring Sunni concerns and governing in the interests of the Shia majority.
Grand Ayatollah Ali al-Sistani's call for a new government to be quickly formed aiming for "broad national acceptance" and to "remedy past mistakes" is being seen as less-than-veiled criticism of the Iraqi PM, correspondents say.
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The BBC released extended video of reporter Paul Wood under fire from Isis in Jalula
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A video posted online by Isis claims to show British and Australian nationals
The UN estimates that about one million people have been displaced within Iraq as a result of violence this year.
About 500,000 people fled their homes in the country's second-largest city, Mosul, which Isis captured last week.
Since then, rebels have made further gains. They claim to have seized parts of Iraq's largest oil refinery, at Baiji, and have also taken seized a disused chemical weapons factory in Muthanna, 70km (45 miles) north-west of Baghdad.
The capture of the border crossing at Qaim in western Iraq could help Isis transport weapons and other equipment to different battlefields, analysts said.
Isis in Iraq
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Isis fighters have been pushing towards Iraq's capital, Baghdad
Isis grew out of an al-Qaeda-linked organisation in Iraq
Estimated 10,000 fighters in Iraq and Syria
Joined in its offensives by other Sunni militant groups, including Saddam-era officers and soldiers, and disaffected Sunni tribal fighters
Exploits standoff between Iraqi government and the minority Sunni Arab community, which complains that Shia Prime Minister Nouri Maliki is monopolising power
Isis led by Abu Bakr al-Baghdadi, an obscure figure regarded as a battlefield commander and tactician
Are you in Iraq or do you have family there? Have you been affected by recent events? You can send details of your experiences to haveyoursay@bbc.co.uk using 'Iraq' in the subject line.
Pro-Russian separatists have carried out several attacks on Ukrainian troops despite a unilateral ceasefire declared by Kiev, Ukrainian officials say.
They say at least six border guards were injured in shelling by the insurgents in the east overnight.
The rebels earlier dismissed the truce called by President Petro Poroshenko, the first step of his peace plan.
Meanwhile, the US imposed sanctions - including asset freezes - against seven pro-Russian leaders in Ukraine.
Western leaders have threatened additional sanctions against Russia, which they accuse of stoking tension in Ukraine. Moscow denies the claim.
In a separate development, President Vladimir Putin ordered forces in Russia's central military district to be put on full combat alert for a week.
The drill does not affect troops near the border with Ukraine. Mr Putin has ordered several such alerts to test combat readiness in recent months.
Buffer zone
Overnight, the separatists attacked three Ukrainian border posts in the Donetsk and Luhansk regions, Kiev said.
The rebels shelled the posts with rocket and mortar fire, injuring six border guards.
The gunmen also attacked Ukrainian forces outside the Kramatorsk airfield, in the Donetsk region.
The Ukrainian forces returned fire, and all the attacks were repelled, Kiev said. However, Ukraine's border guard service said its personnel at the Izvaryne post, Luhansk region, were forced to retreat into Russian territory.
A number of casualties were reported among the separatists.
Mr Poroshenko on Friday declared the week-long ceasefire to give rebels time to disarm. It became effective from 22:00 local time (19:00 GMT).
The president also unveiled proposals for the peace plan involving decentralising power, holding early elections, and creating a 10km (six-mile) buffer zone on the Ukrainian-Russian border.
A senior rebel commander told Ukrainian news agencies the insurgents would not disarm until government troops had left the east.
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Daniel Sandford reports: ''President Poroshenko announced that his forces, which had been gaining ground, will now cease fire for a week''
The Kremlin dismissed the truce, saying it was "not an invitation to peace and negotiations but an ultimatum".
'Scalpel sanctions'
The US and European Union leaders have previously imposed sanctions after Russia annexed the Ukrainian region of Crimea in March.
On Friday, the US Treasury Department said it had blacklisted seven rebel leaders, including self-proclaimed mayors, governors and commanders in chief of cities under siege by Ukrainian forces.
Their assets in the US will be frozen and US firms will be banned from dealing with them.
US officials also said "scalpel" sanctions against Russia's defence, finance and high-tech industries were being considered.
US President Barack Obama had spoken separately to French President Francois Hollande and German Chancellor Angela Merkel, a White House statement said.
The leaders had agreed the US and EU would "co-ordinate additional steps to impose costs on Russia" if Moscow did not try to "de-escalate the situation in eastern Ukraine", the statement added.
Washington says Russia is providing the separatists with military equipment, including tanks, and is building up troops on its border with Ukraine.
Moscow denies the claim.
Are you in Ukraine? How has the crisis in the country affected you? You can send us your experiences by emailing haveyoursay@bbc.co.uk using the subject line "Ukraine".
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Bethany Bell in Cairo says there is "relief" for the 500 who have been spared execution
An Egyptian court has confirmed death sentences for 183 Muslim Brotherhood supporters accused of a 2013 attack on a police station, lawyers say.
A judge had recommended the death penalty for the 683 defendants, in a widely-criticised mass trial in April.
Mohammed Badie, leader of the banned group, was among those whose sentences were upheld. Appeals are now likely.
The military-installed government has sentenced hundreds of its opponents since December.
Authorities have cracked down harshly on Islamists since former President Mohammed Morsi, who belongs to the Muslim Brotherhood, was removed by the military in July 2013 following mass protests.
Saturday's verdict was delivered by a court in the town of Minya, south of Cairo.
Four of the defendants were given sentences of 15-25 years in jail and the rest were acquitted.
The defendants were accused of involvement in the murder and attempted murder of policemen in Minya province on 14 August 2013, the day police killed hundreds of Muslim Brotherhood supporters in clashes in Cairo.
Analysis by Bethany Bell, BBC news, Cairo
This is the largest confirmed mass death sentence to be passed in Egypt in recent times. The verdicts and the speed at which the trial was handled have drawn widespread criticism from human rights groups.
The judge, Sa'ed Yusef Sabri, has a draconian reputation, and is known as al-Jazzar, the Butcher. The activist and former chairman of the Egyptian Organisation for Human Rights, Hesham Qasim, told the BBC it was time for the authorities to take measures against the judge for these unprecedented sentences.
He said the judge had not observed due process, and that once the verdicts were challenged, all the sentences would be overturned. The death sentences, he said, would have a negative impact on Egypt's image around the world and its economy.
The prominent human rights activist, Aida Seif al-Dawla, said the verdicts were politically motivated. The government, she said, was settling its political scores with the Brotherhood through executions.
The charges ranged from sabotage and terrorising civilians to murder. Of the 683, all but 110 were tried in absentia.
Defence lawyers called the mass trial "farcical" and said many of those accused were not present during the clashes.
Following April's trial, the recommended death sentences were referred to the Grand Mufti - Egypt's top Islamic authority - for review.
The court was to consider his opinion before issuing its final decision.
However correspondents say the case is likely to go to Egypt's appeal courts.
On Thursday, Mr Badie and 13 others were also given recommended death sentences over a separate case involving deadly clashes last year.
The next phase of the hunt for missing Malaysian jet MH370 will move hundreds of miles south, officials have said.
The search will focus on an area 1,800km (1,100 miles) off the city of Perth, Australian Transport Safety Bureau (ATSB) chief Martin Dolan said.
Nearby areas were previously surveyed from the air, but the undersea hunt was directed north after pings were heard.
The jet vanished en route from Kuala Lumpur to Beijing on 8 March with 239 passengers on board.
Experts had hoped that the pings detected shortly after the plane vanished were from its flight-data recorders.
But after weeks of searching the ocean floor, it was concluded that the noises were unrelated to the plane.
Analysis: Jonathan Amos, science correspondent, BBC News
The new search area(s) that the ATSB promise to announce shortly must be tied to the ocean-bed mapping now being conducted by survey ships. Their information is critical to guiding underwater sweeps. Without proper depth data, you cannot choose the most appropriate submersibles to look for MH370 wreckage.
The Australian authorities tell me that the Dutch-owned Fugro Equator is currently working in an area located along the arc where Inmarsat made a seventh and final connection with the lost jet.
China's Zhu Kezhen is currently in transit and should arrive on station within hours. It will use its echosounder equipment to map an area to the north of Fugro Equator. Together, these ships will describe the exact shape of the sea floor. In places, it is thought to be more than 6km deep.
Search teams have now returned to the initial satellite data to frame the new search area.
"All the trends of this analysis will move the search area south of where it was," Mr Dolan said.
"Just how much south is something that we're still working on."
Painstaking mapping
They expect to make an announcement next week on exactly where the search will take place.
He said it was unlikely the new focus would be as far from land as the aerial surveys had been.
UK firm Inmarsat told the BBC this week that their data had pointed to a "hotspot" - a crash zone of highest probability - to the south-west of the recent undersea search.
But Inmarsat's analysis is just one of several being used within the investigation team.
Before search teams can start looking for the plane, the seabed will be mapped.
This is being done by Chinese and Dutch vessels.
The ocean in this part of the globe is more than 6km deep in places, and the survey is likely to take three months to complete.
Many of the relatives of the missing passengers have been frustrated by the lack of progress in the search.
What frustrates me is the suffering of people, to see so many innocent people dying... and the world being unable to put an end to this nonsense"
End QuoteAntonio GuterresUN High Commissioner for Refugees
People living in what the UN terms "protracted" refugee situations include more than 2.5 million Afghans. Afghanistan still accounts for the world's largest number of refugees, and neighbouring Pakistan is host to more refugees than any other country, with an estimated 1.6 million.
Around the world, thousands of refugees from almost forgotten crises have spent the best part of their lives in camps. Along Thailand's border with Burma, 120,000 people from Burma's Karen minority have lived in refugee camps for more than 20 years.
Refugees should not be forcibly returned, the UN says, and should not go back unless it is safe to do so, and they have homes to return to. For many - among them the more than 300,000 mainly Somali refugees in Kenya's Dadaab camp - that is a very distant prospect.
Some camps, the UN refugee agency admits, have become virtually permanent, with their own schools, hospitals, and businesses. But they are not, and can never be, home.
But the world's refugees are far outnumbered by the internally displaced (IDP) - people who have been forced to flee their homes, but remain inside their own countries.
In Syria alone there are thought to be 6.5 million displaced people. The conflict has uprooted many families not once but several times. Their access to food, water, shelter and medical care is often extremely limited, and because they remain inside a conflict zone, it is hard for aid agencies to reach them.
Worldwide, the UN estimates there are now 33.3 million internally displaced people.
Large numbers of refugees and IDPs fleeing to new areas inevitably put a strain on resources, and can even destabilise a host country.
Throughout the Syrian crisis, Lebanon, Jordan and Turkey have kept their borders open. Lebanon now hosts more than a million Syrian refugees, meaning a quarter of its total population is Syrian. The pressure on housing, education and health is causing tensions in a country which itself has a recent history of conflict.
The UN is concerned that the burden of caring for refugees is increasingly falling on the countries with the least resources. Developing countries are host to 86% of the world's refugees, with wealthy countries caring for just 14%.
And despite the fears in Europe about growing numbers of asylum seekers and immigrants, that gap is growing. Ten years ago wealthy countries hosted 30% of refugees, and developing countries 70%.
Antonio Guterres believes Europe can and should do more.
"I think it's very important that Europe fully assumes its responsibilities," he said.
"I think it's also clear that we have in Europe good examples, Sweden, Germany, have taken very generous measures… but we need a joint expression of European solidarity."
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Kim Ghattas reports on the "forgotten plight" of Afghan refugees
But what frustrates UN aid agencies most of all is being asked to cope with ever more refugees, while the UN's political arm, the Security Council, seems unable either to resolve conflicts, or to prevent them starting.
"The world is becoming more violent, and more people are being forced to flee," said Mr Guterres, adding that humanitarian organisations had neither the capacity nor the resources to cope.
"There is no humanitarian solution to these problems… to see the Security Council paralysed, when all these crises are evolving, is something that doesn't make sense."
"What frustrates me is the suffering of people, to see so many innocent people dying, so many innocent people fleeing, so many innocent people seeing their lives completely broken, and the world being unable to put an end to this nonsense."
A car bomb has killed at least 34 people in a Syrian government-controlled village in central Hama province, state media say.
More than 50 people were reportedly hurt in the attack in Horra village.
The state news agency, Sana, blamed the bombing on rebels who have been fighting to overthrow President Bashar al-Assad.
More than 160,000 people are estimated to have been killed in Syria's three-year-long uprising.
Another 9.5 million people, or almost half the population, have been driven from their homes.
The Syrian uprising began in 2011 with peaceful protests inspired by the Arab Spring.
It has become a civil war, pitting government forces against rebel factions, many of whom are inspired by Islamist and sectarian rhetoric.
The UK-based activist group, the Syrian Observatory for Human Rights, says the death toll in the Horra bombing is likely to rise as many of the injured are in a critical condition.
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Jim Muir visited the outskirts of Mosul to see how people have been coping
Islamist-led militants and pro-government forces are engaged in fierce battles for the Baiji oil refinery and Tal Afar airport in northern Iraq.
Baiji, Iraq's biggest refinery, is surrounded by the rebels, who say they have seized most of Tal Afar airport.
The fighting comes a day after the US said it would send some 300 military advisers to help the fight against the insurgents.
President Barack Obama stressed that US troops would not fight in Iraq.
US Secretary of State Kerry is expected to travel to Iraq soon to press for a more representative cabinet, hoping this could ease tensions between the country's rival Muslim sects.
Iraqi Prime Minister Nouri Maliki has been accused of pursuing anti-Sunni policies, pushing some Sunni militants to join the jihadist Islamic State of Iraq and the Levant (ISIS), which has made rapid advances in recent days.
About 500,000 people have fled their homes in the country's second-largest city, Mosul, which ISIS captured last week.
Analysis: John Simpson, BBC News, Baghdad
President Obama's statement wasn't the lifeline the Iraqi government hoped for. They wanted immediate airstrikes to stop ISIS in its tracks.
Instead, they will get up to 300 military advisers, who will restore the backbone to the Iraqi National Army which it has been missing since the Americans withdrew. The promise of air strikes is there, but attacks by US planes or missiles will, it seems, be dependent on some clear improvement in the way Iraq is governed; even though Mr Obama wouldn't say so.
He believes Prime Minister Nouri Maliki has endangered Iraq by ignoring Sunni concerns and governing in the interests of the Shia majority. Mr Maliki's supporters deny this and say he won't resign, but rivals to him are said to be emerging.
The least Mr Maliki will have to do is create a new and more inclusive government. Only then, perhaps, will the bombing start.
ISIS says it has downed two military helicopters around the Baiji refinery but this has not been independently confirmed.
The BBC's Jim Muir in Irbil, northern Iraq, says it is thought the militants may have captured part of the vast oil complex.
They have also seized a disused chemical weapons factory in Muthanna, 70km (45 miles) north-west of the capital, Baghdad.
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Reda El Mawy reports from a warehouse preparing aid for people in Irbil
The US says it does not believe the site contains any material that the insurgents could use to make chemical weapons.
But state department spokeswoman Jen Psaki said: "We remain concerned about the seizure of any military site by" ISIS.
Iraq has asked the US for air strikes against the Sunni militants.
Mr Obama said the US was prepared for "targeted and precise military action, if and when" required, but he insisted there was "no military solution" to the crisis.
He also pointedly urged the Shia-led Iraqi government to be "inclusive".
Mr Obama said it was not the US's place to choose Iraq's leaders but warned:
"Only leaders with an inclusive agenda are going to be able to truly bring the Iraqi people together.
"The United States will not pursue military actions that support one sect inside of Iraq at the expense of another," Mr Obama said.
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The BBC released extended video of reporter Paul Wood under fire from ISIS in Jalula
ISIS in Iraq
ISIS grew out of an al-Qaeda-linked organisation in Iraq
Estimated 10,000 fighters in Iraq and Syria
Joined in its offensives by other Sunni militant groups, including Saddam-era officers and soldiers, and disaffected Sunni tribal fighters
Exploits standoff between Iraqi government and the minority Sunni Arab community, which complains that Shia Prime Minister Nouri Maliki is monopolising power
ISIS led by Abu Bakr al-Baghdadi, an obscure figure regarded as a battlefield commander and tactician
In addition to sending advisers, Mr Obama said that the US would be increasing intelligence efforts and setting up "joint operation centres in Baghdad and northern Iraq".
Thousands of Shia from southern Iraq have volunteered to help the Iraqi army.
Shia militiamen have been sent to assist in the defence of the capital of Diyala province, which has in effect become a frontline, and the nearby city of Samarra, site of a major Shia shrine.
On Wednesday, the chairman of the US Joint Chiefs of Staff, Gen Martin Dempsey, warned that the US military still lacked sufficient intelligence to take action. He told a congressional hearing that pilots would have difficulty knowing who they were attacking from the air.
Iraq and the Sunni-Shia divide
Sunnis and Shia share fundamental beliefs, but differ in doctrine, ritual, law, theology and religious organisation
The origins of the split lie in a dispute over who should have succeeded the Prophet Muhammad as leader of the Muslim community
Sunnis are the majority sect in the Muslim world, but Shia, most of them ethnic Arabs, form between 60% and 65% of Iraq's population; Sunnis make up 32-37%, split between Arabs and Kurds
Sunni Arabs dominated Iraq under Saddam Hussein and their persecution of the Shia stoked sectarian tensions; the US-led invasion in 2003 gave the Shia an opportunity to seek redress
Nouri Maliki has been accused of denying Sunni Arabs meaningful representation and pursuing security policies that target them
Are you in Iraq or do you have family there? Have you been affected by recent events? You can send details of your experiences to haveyoursay@bbc.co.uk using 'Iraq' in the subject line.
Written By Unknown on Selasa, 17 Juni 2014 | 18.19
17 June 2014Last updated at 11:30
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LIVE: UK foreign secretary takes MPs' questions on issues including Iraq and re-opening the Iran embassy
Foreign Secretary William Hague has said he intends to re-open Britain's Embassy in the Iranian capital Tehran.
Mr Hague said the "circumstances were right" following an improvement in bilateral relations in recent months.
Full diplomatic relations with Iran were suspended after attacks on the British embassy in Iran in 2011.
The election of a new Iranian president and agreement on how to deal with Iran's nuclear programme has led to increased contacts in 2014.
The move comes as Iraqi forces are engaged in heavy clashes with Sunni Islamist militants across the country and amid reports that Iran is providing military assistance to its historic rival.
The US is deploying up to 275 military personnel to protect staff at its huge embassy in Iraq.
In a written statement, Mr Hague said the UK embassy will re-open "as soon as practical arrangements are made" as a sign of "increasing confidence" in the state of relations between the two countries.
"There has never been any doubt in my mind that we should have an embassy in Tehran if the circumstances allowed," he said.
"Iran is an important country in a volatile region, and maintaining embassies around the world, even under difficult conditions, is a central pillar of the UK's global diplomatic approach."
The foreign secretary, who is currently giving further details to MPs, said he had sought assurances that British diplomatic staff would be safe and would be able to carry out their work "without hindrance".
Analysis by Kasra Naji, BBC Persian
Efforts to establish normal relations between UK and Iran were stepped up last year soon after the election of President Hassan Rouhani. He had promised to mend Iran's relations with the outside world.
Iran's relations with many countries had taken a turn for the worse during the previous eight years of disastrous foreign policy adventures under President Mahmoud Ahmadinejad.
It was on his watch that angry Islamic hard-line supporters of the government attacked and ransacked British embassy buildings in Tehran in November 2011. Now the two countries are trying to put all that behind them. Both countries need each other, and it seems the need for co-operation on stopping the advance of Isis in Iraq has given the efforts to improve relations a new impetus.
Britain needs Iran to help establish a broad-based government in Iraq. But there are still unresolved problems. Iran says it will not apologise for the attack that broke all diplomatic norms, although it says it is willing to discuss paying for the damages to the buildings.
The safety of Iranian staff working for the British embassy is another issue that needs firm guarantees from the Iranian side. But for ordinary people, the reopening of the embassies cannot come soon enough.
Tens of thousands of Iranians, many of them students, live in Britain. They and their families need visas and consulate services that they are not getting at the moment.
The shared interest in confronting militants led by the Islamic State in Iraq and the Levant (ISIS) has accelerated contacts between the West and Iran.
BBC political editor Nick Robinson said William Hague spoke to Iran's foreign minister over the weekend.
While there had been a gradual detente in relations in recent months, events in Iraq had given the process a "mighty great shove", he added.
'Partner'
Former foreign secretary Jack Straw welcomed the move, which he said would have come at some stage but had been "accelerated" by developments in Iraq.
"I hope it will lead to a new strategic approach to see Iran as much more of a partner than an adversary," he told the BBC News Channel.
Former senior diplomat Sir William Patey told Radio 4's Today programme that it was potentially a "very significant moment" for dealings between the two countries.
"Iran is often seen as the enemy and has seen us as the enemy," he said.
"Against a backdrop of an improving relationship with the prospect of a nuclear deal, there is a prospect of having a more constructive relationship with Iran because there is a bigger enemy - which is Isis."
However, he warned the "potential for falling out with Iran is always very high".
The storming of the British embassy in 2011, in retaliation for UK support for sanctions against Tehran, was one of series of incidents in the past decade that have ratcheted up tensions between the countries.
In 2007, 14 Royal Navy sailors were detained by the Iranian authorities after they were accused of violating Iranian territorial waters.
The appointment of a UK-based British charge d'affaires to Tehran last year was seen as a sign of a thaw in relations and paving the way for the possible re-opening of the embassy.
However, the UK government still has concerns about Iran's role in Syria, where it is supporting the government of Bashar al-Assad in its fight against rebel groups and its backing for Hezbollah in Lebanon.
The US broke off diplomatic relations with Iran in 1980 after 52 of its embassy staff were held hostage in Tehran.
17 June 2014Last updated at 01:20By Jonathan AmosScience correspondent, BBC News
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Pallab Ghosh reports on the latest twist in the search for MH370
The UK satellite company Inmarsat has told the BBC that the search for the missing Malaysia Airlines jet has yet to go to the area its scientists think is the plane's most likely crash site.
Inmarsat's communications with the aircraft are seen as the best clues to the whereabouts of Flight MH370.
The hunt for the lost jet is currently taking a short break while ships map the Indian Ocean floor.
When the search resumes, the Inmarsat "hotspot" will be a key focus.
But so too will a number of areas being fed into the investigation by other groups.
Australian authorities are expected to announce where these are shortly.
The BBC's Horizon TV programme has been given significant access to the telecommunications experts at Inmarsat.
It was the brief, hourly electronic connections between the jet and one of company's spacecraft that are currently driving the search.
Inmarsat's scientists could tell from the timings and frequencies of the connection signals that the plane had to have come down in the southern Indian Ocean.
An Australian naval vessel was sent to investigate the region west of Perth, and followed up leads as they emerged.
But as Horizon reports, the Ocean Shield ship never got to the Inmarsat hotspot because it picked up sonar detections some distance away that it thought were coming from the jet's submerged flight recorders.
The priority was to investigate these "pings", and two months were spent searching 850 sq km of sea bed. Ultimately, it turned out to be a dead end.
"It was by no means an unrealistic location but it was further to the north east than our area of highest probability," Chris Ashton at Inmarsat tells Horizon.
The company's experts used their data to plot a series of arcs across the Indian Ocean where its systems made contact with the jet.
By modelling a flight with a constant speed and a constant heading consistent with the plane being flown by autopilot - the team found one flight path that lined up with all its data.
"We can identify a path that matches exactly with all those frequency measurements and with the timing measurements and lands on the final arc at a particular location, which then gives us a sort of a hotspot area on the final arc where we believe the most likely area is," said Mr Ashton.
The Australian authorities leading the hunt have now recognised the need to make a high-resolution bathymetric (depth) survey of the wider search zone - some 60,000 sq km in area.
This is likely to take several months, but once they know precisely the shape of the sea bed and the height of the water column, they can then better choose the most appropriate vehicles to continue the underwater sweep.
MH370 was lost on 8 March en route from Kuala Lumpur to Beijing. A total of 239 passengers and crew were on board.
