Hard-left Jewish Labour activists claim their meetings are being broken up by right-wing “vigilantes”.

Richard Kuper, a supporter of the left-wing Free Speech On Israel (FSOI), said Jews who were critical of Israel and wanted to debate definitions of antisemitism were often prevented from doing so by other Jews.

“Not every Jewish person has the same opinion on Israel. There are Jews out there who want to be able to criticise Israel without being attacked,” he said.

Mr Kuper said the widely accepted International Holocaust Remembrance Alliance definition of antisemitism was preventing legitimate criticism of Israel.

“There are vigilantes out there who feel emboldened because of it. They try to break up meetings and stop Jews who want to debate Israel.”

According to FSOI’s website, two of its meetings in the past six months were disrupted by pro-Israel activists.

Mr Kuper, who was a founding member of Jews for Justice for Palestinians, said: “A meeting at the House of Commons was broken up by people who intimidated other Jews. We haven’t asked the Community Security Trust to protect these sorts of meetings, but Jews should feel safe enough to discuss these things when we want to.”

FSOI said the Commons event in December had been intended to give “rarely heard Jewish voices a platform from which to explain that, while the kind of anti-Jewish hatred that led to the obscenity of the Holocaust had to be confronted head on, alleging that criticism of Israel is necessarily antisemitic is counterproductive”.

Mr Kuper claimed that at another event held in London last November, hard-left Jews who criticised Israel were called “kapos” - the label applied to Jews who helped the Nazis run death camps.