Hamas have said an Israeli soldier with links to the UK may have been killed in a strike on his captors by the Israeli military, Hamas has said.
At least 47 people were killed as Israel launched fresh attacks on Gaza overnight amid the continued hunt for the "kidnapped" Israeli soldier.
Officials in Palestine said 37 of those killed died in Israeli strikes on Rafah, where the soldier, Hadar Goldin, went missing.
The military wing of the Palestinian organisation said in a statement on its website it was "not aware until this moment of a missing soldier or his whereabouts or the circumstances of his disappearance".
Israel earlier claimed Second Lieutenant Goldin had been kidnapped an hour after the start of a humanitarian ceasefire, but Hamas has denied holding the soldier and instead claims it lost contact with its fighters following a clash in southern Gaza.
"We believe all members of this group have died in an (Israeli) strike, including the Zionist soldier the enemy says disappeared," the statement read.
The Israeli military declined to comment on the statement.
Meanwhile, questions were being asked about whether military equipment manufactured in the UK has been used in Israel's offensive on the Palestinian enclave.
Documents obtained by The Independent showed that arms export licences worth £42 million have been granted to 130 British defence manufacturers since 2010 to sell military equipment to Israel, ranging from weapons control and targeting systems to ammunition, drones and armoured vehicles.
The Government said it was reviewing all licences to Israel, but a Labour MP said ministers were "burying their heads in the sand" over the issue of whether UK-manufactured weapons or components have been used in Gaza since the current round of hostilities began three weeks ago.
At least 1,600 Palestinians - most of them civilians - have been killed and 8,000 injured during the assault, while Israel has lost 63 soldiers and three civilians.
The planned ceasefire was shattered early yesterday, with each side blaming the other, and the situation escalated with the apparent capture of Lt Goldin. The Foreign Office was looking into claims that Lt Goldin held joint Israeli-British citizenship, though Foreign Secretary Philip Hammond said "no evidence" had been found to back up the assertion.
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US president Barack Obama and United Nations secretary general Ban Ki-moon called for the soldier's immediate release but also urged restraint on all sides as Israeli troops pressed deeper into Gaza in the search for him.
Mr Hammond said: "If the reports that Hamas broke the ceasefire are correct then that is very serious indeed, as is the kidnapping of the Israeli soldier which will make it all the more difficult to re-establish the ceasefire to allow a humanitarian pause in Gaza."
Rabbi Reuven Leigh, a chaplain at Cambridge University and a rabbi in the local community, said Lt Goldin - who has a twin brother also serving with the Israeli military in Gaza - had lived in the city for a number of years.
"Shaken to hear of Hadar Goldin's kidnapping, he spent a few years living in Cambridge with his family, please pray for his safe return," he wrote on his Twitter feed.
Israeli prime minister Benjamin Netanyahu told US secretary of state John Kerry that Palestinian militants had "unilaterally and grossly" violated the ceasefire and attacked Israeli soldiers.
"Israel will take all necessary steps against those who call for our destruction and perpetrate terrorism against our citizens," he said.
Mr Obama said he would continue working towards a ceasefire and called on Israel to take steps to prevent Palestinian civilian casualties, saying: "Innocent civilians caught in the crossfire have to weigh on our conscience, and we have to do more."
Labour leader Ed Miliband said that David Cameron had put himself "in the wrong place" over Gaza by failing to make clear to Israel from the outset that its incursion would not resolve its problems with rocket attacks launched by Hamas from the territory.
Mr Miliband told LBC radio: "If I was David Cameron... I would be spending my time on doing everything I can to put pressure on both sides to have that ceasefire that is required.
"I think he is in the wrong place on this, because I agree with him about Hamas - Hamas is a terrible and disgusting organisation - but I think he should have said from the outset that this incursion by Israel into Gaza was not going to solve the problem. It isn't solving the problem, it's making it worse.
Meanwhile, Mr Miliband's brother David, the former foreign secretary and president of the International Rescue refugee charity, said that the focus of attention should be on the 1.8 million civilians in Gaza trapped inside a war zone.
Asked if Israel's deployment of military force had been "disproportionate", David Miliband told BBC2's Newsnight: "Of course. Eighty per cent of the casualties in this war have been civilians, and as the leader of a humanitarian movement, I have to defend the principle that after centuries in which civilians were caught in the crossfire of war, finally in 1949 the Geneva Convention established the absolute right to defence for civilians during war, and that is being broached.
"The heartbreaking, the heart-rending situation which faces the people of Gaza tonight is that 1.8 million of them are trapped in an area where frankly there is no safe zone, and that is completely contrary to every basic fibre of being that anyone can understand or uphold."
Official data obtained by the Campaign Against Arms Trade under the Freedom of Information Act showed that of the £42 million "military list" exports to Israel approved since 2010, some £10 million were licensed in the last 12 months.
Among manufacturers given permission to make sales were UK companies making components for the Hermes drone aircraft and Israel's main battle tank, reported The Independent. The sales are entirely lawful and make up part of a £12 billion British arms export trade.
Andrew Smith, of CAAT, told the newspaper: "There must be an immediate embargo on all arms sales and military collaboration with Israel. When governments sell weapons into war zones they cannot absolve themselves of responsibility for what happens when they are used."
And Labour MP Katy Clark said that ministers must establish whether any of the weapons or components have been used in Gaza, adding: "By refusing to investigate this vital question the British Government are trying to bury their heads in the sand. This is a shameful approach to take and frankly makes the Government look as if it has something to hide.
"The British public have the right to know the level of support which the United Kingdom has provided to the Israeli armed forces through arms sales."
A government spokesman said: "We are currently reviewing all existing export licences to Israel. All applications for export licences are assessed on a case by case basis against strict criteria. We will not issue a licence if there is a clear risk that the equipment might be used for internal repression, or if there is a clear risk that it would provoke or prolong conflict."
Deputy Prime Minister Nick Clegg urged Israel to halt its military operations and talk to Hamas.
The Liberal Democrat leader said that the Israeli military action "appears disproportionate" and would not succeed in delivering security for its people.
Writing in The Guardian, Mr Clegg said: "If Israel wants to secure lasting safety for its people, it must use political will, not military might, to break the cycle of violence.
"Prime minister Binyamin Netanyahu must now put Israel's long-term, strategic self-interest ahead of short-term, tactical military gains. It is time for the Israeli government to talk to the Hamas political leadership in Gaza. Israel's refusal to engage with president Mahmoud Abbas's new unity government, because it includes Hamas, must be reversed."
Mr Clegg said neither side could escape blame for the current crisis, but suggested Israel could win international support with "an unexpected act of political magnanimity, rather than sporadic military reprisal".
"It is difficult to deny that Israel's military action appears disproportionate and, combined with the Gaza blockade, is resulting in the collective suffering of the Palestinian people," he wrote. "Hamas cannot escape blame either. By hiding among the civilian population and stashing weapons in schools and mosques, it has shown it is willing to sacrifice its own people for military advantage."
Former Lib Dem leader and peace envoy Lord Ashdown told BBC Radio 4's Today programme that Israel should speak to Hamas.
"Neither side can blast their way to victory, so there is only one way to get peace now, and that is for the sides to sit down and start talking to each other," said Lord Ashdown.
"Hamas has to be at the table. Who's firing the rockets? It's Hamas, and so you have to talk to them... If an individual or an organisation has the support of the people who it represents, in the end you have to talk to them. We had to talk to the IRA, for goodness' sake."
Lord Ashdown said there was "no question" that Israel's military action was disproportionate, telling Today: "You have to call a spade a spade. Is it disproportionate? Yes it is, there's no question about it.
"Israel makes the excuse that because weapons are being fired from civilian areas, it's entitled to use indiscriminate total force against civilian areas. No you're not. Our troops in Afghanistan and Northern Ireland had this constantly going on - if they'd used total force against a whole civilian area because somebody had fired from it, they would have been guilty of a crime. That's not an excuse.
"To have accidentally, in the course of trying to be careful, hit a single UN school and haven, you could put down to an error in the process of trying to be careful. But to hit six, you have to conclude that's either criminally careless or carelessly indiscriminate."
Lord Ashdown described Israel's military action as "really foolish", adding: "They have had in total from thousands of Hamas rockets just two civilians killed. They've multiplied that to 60 by this operation - they've lost 60 of their own and killed thousands of Palestinians, thousands of people in Gaza, created hundreds if not thousands of terrorists, created the enmity of the entire Middle East and lost the support and sympathy of world opinion. That doesn't seem to me to be a very good dividend from military action."