As the hunt continued for an Israeli officer captured in Gaza, 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.
A planned ceasefire was shattered early yesterday, with each side blaming the other, and the situation escalated with the apparent capture of Second Lieutenant Hadar 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.
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."