Westminster-based lobby group Labour Friends of Israel (LFI) has described the Palestinian refugees' right of return as "extreme and illegitimate", in a letter to Labour leader Jeremy Corbyn this week.
LFI's letter came in response to remarks made by the Leader of the opposition on 25 June, during a recent visit to Jordan. In a Twitter post, Corbyn wrote:
"In Jordan, I went to Baqa'a, one of the largest Palestinian refugee camps. We must work for a real two state settlement to the Israel-Palestine conflict, which ends the occupation and siege of Gaza and makes the Palestinian right to return a reality."
In the period 1947-1949, hundreds of thousands of Palestinians were expelled from or fled their homes as Zionist militias and the Israeli army destroyed hundreds of villages in what became Israel. Refugees attempting to return were killed, and Israel passed laws to expropriate their properties.
Corbyn's expression of support for the Palestinian refugees' internationally-recognised rights, prompted anger and concern from British pro-Israel groups, including LFI.
In a letter from LFI chair MP Joan Ryan, the pro-Israel group describes the Palestinians' right to return (which is referred to in scare quotes) as "highly contentious", and at odds with Israel's insistence on retaining its Jewish majority of citizens.
Ryan added: "I do not believe that it does anything to encourage the compromises and concessions a future negotiated settlement will involve for foreign politicians to appear to endorse the most extreme and illegitimate demands of either side."
The LFI chair concluded by urging Corbyn to "immediately clarify" what he understands by a right to return, and to only use "language…[that] helps to advance, not hinder, the cause of peace, reconciliation and coexistence between Israelis and Palestinians."
A spokesperson for the Labour party said: "These rights are inalienable and guaranteed by UN Resolution 194 of 11 December 1948. How the right of return is implemented is a matter for the negotiations between the Israelis and Palestinians."