Nearly 60 Labour MPs have demanded the UK immediately recognises Palestine as a state, after Israel's defence minister announced plans to force all residents of Gaza into a camp on the ruins of Rafah.
The MPs, who include centrist and leftwing backbenchers, sent a letter to David Lammy on Thursday warning they believed Gaza was being ethnically cleansed.
They are urging the foreign secretary to take immediate steps to prevent the Israeli government from carrying out its Rafah plan, and to go further and recognise Palestinian statehood immediately.
The letter was sent just after the French president, Emmanuel Macron, made a similar plea at a joint press conference with Keir Starmer, the UK prime minister.
The MPs wrote: "It is with great urgency and concern that we are writing to you regarding the Israeli defence minister's announcement on Monday of his plans to forcibly transfer all Palestinian civilians in Gaza to a camp in the ruined city of Rafah without allowing them to leave."
They added: "The defence minister's plans have been described by a leading Israeli human rights lawyer, Michael Sfard, as 'an operational plan for crimes against humanity. It's about population transfer to the southern tip of Gaza in preparation for deportation outside the strip.'
"Though an accurate description, we believe there is a clearer one. The ethnic cleansing of Gaza."
The letter calls for ministers to take five different measures. The government is already pursuing some of those, such as providing funding for the UN agency for Palestinian refugees, Unrwa, and working to secure the release of hostages held by Hamas.
Others, however, are likely to prove more controversial, including imposing a trade blockade on Israeli settlements in the West Bank and immediate recognition of Palestinian statehood.
"By not recognising [Palestine] as a state, we undermine our own policy of a two-state solution and set an expectation that the status quo can continue and see the effective erasure and annexation of Palestinian territory,"
the MPs warned.
Ministers plan to recognise Palestine as part of a peace process, but only in conjunction with other western countries and "at the point of maximum impact" - without saying what that is.
A foreign office spokesperson said: "We are committed to recognising a Palestinian state and to doing so when [it] will have most impact in support of a peace process."
Several European countries have already granted recognition, while France, which has not yet done so, has recently been putting pressure on Britain and other allies to do so in tandem.
Speaking at the end of his three-day state visit to the UK this week, Macron said: "Calling today for a ceasefire in Gaza without any condition is telling the rest of the world that for us as Europeans, there is no double standard. As we are attached to human lives, as we are attached to territorial integrity, we want the ceasefire, no discussion."
He added: "Today, working together in order to recognise the state of Palestine and to initiate this political momentum is the only path to peace."
The letter is the second time in recent weeks Labour MPs have written to ministers calling for them to recognise Palestine, but the first time they have been willing to make their names public. A previous letter also included the names of some parliamentary aides and junior ministers.
The letter was organised by Labour Friends of Palestine and the Middle East and signed by 59 MPs, including the group's two chairs, Sarah Owen and Andrew Pakes. Other signatories include Liam Byrne, who chairs the business select committee, and Tanmanjeet Singh Dhesi, as well as the prominent backbenchers Stella Creasy, Clive Lewis, Diane Abbott and Dawn Butler.
The Foreign Office has been contacted for comment.