The shadow foreign secretary, David Lammy, has said he has “serious concerns about a breach in international humanitarian law” over Israel’s actions in Gaza as “far too many people have died”. At least 33,037 Palestinians have been killed and 75,668 others have been injured in the Israeli military offensive, according to the Palestinian health ministry, six months on from the 7 October Hamas attack in southern Israel, during which about 1,140 people were killed and 240 others were taken as hostages. The conflict appears to have opened a rift within Rishi Sunak’s cabinet, with the foreign secretary, David Cameron, warning the UK’s support for Israel is “not unconditional”. But the deputy prime minister, Oliver Dowden, said Israel was being held to “incredibly high standards”. The day after the 7 October attack, Lammy said Israel must do “what it must do, but within the bounds of international law”. Other senior Labour figures noted at the time that Israel must always have the right to defend itself after Israel said: “No electrical switch will be turned on, no water hydrant will be opened and no fuel truck will enter” until the hostages were free . But speaking on Sunday, Lammy said: “As we sit here six months later, I think it is important to reaffirm that a life lost is a life lost whether that is a Muslim or a Jew.” “Let me begin because Elad Katzir, one of the hostages, we now know is dead and we saw protests in Israel overnight. It is important to remember that there are well over 100 hostages, some may no longer be alive, in Gaza. And this story began with that horrific event on 7 October,” Lammy told Sky News’ Sunday Morning with Trevor Phillips programme. He added: “I think it is serious when we have senior judges who are on our supreme court who raise issues about the clear risk of breaches in international law, former head of the MI6 Sir Alex Younger says the same, and of course, I’ve said that I have serious concerns about a breach in international humanitarian law in regard to this.” For that reason Lammy has reiterated a call for Lord Cameron to publish any legal advice the UK government had received and to reveal whether Downing Street had instructed him not to do so. Lammy suggested “on issues of war”, a Labour government would publish a “summary of legal advice”, as the Sunak government did after the UK took action against the Houthis. But the shadow foreign secretary refused to back a call from the London mayor, Sadiq Khan, and Scottish Labour leader, Anas Sarwar, for the UK to ban arms sales to Israel immediately. Labour will push for an end to arms sales only if legal advice provided to ministers shows continued sales could risk the UK breaching international law. Cross-party MPs, including 50 Labour MPs, have piled pressure on the government to act after seven international aid workers, including three British citizens were killed by an Israeli airstrike in Gaza on Monday. Lammy has accused Cameron of dodging scrutiny on the UK’s arms sales to Israel and urged him to appear in the Commons to answer MPs directly on arms export licences. Cameron warned on Saturday night that Britain’s support for Israel was not unconditional and cautioned Israel’s prime minister Benjamin Netanyahu that the attacks that killed aid workers “must never happen again”. But Dowden has taken Sunak’s line of standing by Israel’s right to defend its security while urging people to remember the “trauma” Israelis are suffering. The deputy prime minister said Britain was not giving the IDF “carte blanche”, adding: “The manner in which some people are seizing on this issue and trying to hold Israel to incredibly high standards, of course it is right that we hold Israel to high standards, but I just think there is a bit of relish from some people about the way in which they are pushing this case against Israel.” He later suggested on BBC One’s Sunday with Laura Kuenssberg show that the UK would stop arms sales to Israel if it was found in breach of international law. Dowden insisted there were no government plans to change export rules, after the Observer obtained a leaked recording of the Conservative chair of the Commons foreign affairs select committee, Alicia Kearns, saying the government had received advice from its own lawyers stating that Israel had breached international humanitarian law in Gaza but had failed to make it public. Meanwhile, Lord Dyson, a former master of the rolls and supreme court justice, joined 1,100 lawyers calling on the UK to reject calls to impose an arms embargo on Israel. In a letter to Sunak organised by UK Lawyers for Israel (UKLFI), they criticised former supreme court justices who said the situation in Gaza was “catastrophic” and for their reliance on “Hamas supplied casualty figures”. Guardian Newsroom: Crisis in the Middle East On Tuesday 30 April, 7-8.15pm GMT, join Devika Bhat, Peter Beaumont, Emma Graham-Harrison and Ghaith Abdul-Ahad as they discuss the fast-developing crisis in the Middle East. Book tickets here or at theguardian.live