The UK should pause arms sales to Israel to prevent British weapons being used in an offensive in Rafah, a Labour frontbencher said.
Jonathan Ashworth also demanded the Government publish legal advice on whether Israel is sticking to international law. It comes after Foreign Secretary David Cameron said halting arms exports wouldn't be a "wise path" to follow.
Mr Ashworth, the Shadow Paymaster General, told the BBC's Sunday with Laura Kuenssberg: "If the full scale offensive goes ahead, I do not want to see British made weapons or components that are parts of weapons used in the offensive. So we both called for the legal advice to be published. That's unprecedented, but in the circumstances, we think it should be published.
"But we do not think that those arms sales should go ahead." Joe Biden has already said that the US will stop providing bombs and ammunition to Israel if an attack on the heavily-populated city goes ahead. Israel has urged residents in more areas of Gaza's southern-most city to evacuate in a further sign its military is preparing for a ground incursion.
Lord Cameron has said that the UK does not support an Israeli assault on Rafah without a detailed plan to protect civilians. But he stopped short of threatening to provide arms to Israel.
Happy Valley's James Norton teases Tommy's 'deep hatred' in final seriesMr Ashworth told Sky News: "We should be pausing arms sales in order to stop any arms that would be used in that Rafah offensive. We do not want this Rafah offensive to go ahead, it would be completely catastrophic.
"The Americans have said they are not going to hand over arms which could be used in a Rafah offensive. I am saying that we should adopt a similar position."
Labour MP Zara Sultana told Ms Kuenssberg: "W hen we look at the role that we're playing, we are aiding and abetting war crimes that are happening on a daily basis."
Lord Cameron continued to downplay the amount of weaponry the UK provides to Israel, but said this is kept under review. He said: "The UK provides less than 1% of Israel's weapons and it's not a state supplier. We have a licensing system and those licences can be closed if it's judged there's a serious risk of a serious international human rights violation."
The US State Department on Friday said there was "reasonable" evidence that Israel had breached international law protecting civilians. Asked by Sir Trevor about following the US example, Lord Cameron said: "I don't think it would have been a wise path, and I still don't think it would be a wise path," he said, adding it would "strengthen Hamas".
Green MP Caroline Lucas posted on X: "Sickening to watch Cameron attempting to defend the indefensible - turning evasion and obfuscation into an art form. Govt’s refusal to end arms exports to Israel makes UK complicit in war crimes..."