Jewish groups in Britain planned a protest outside Parliament on Monday, accusing the country's main opposition leader of failing to stamp out anti-Semitism within his left-of-center party.
Since unexpectedly becoming Labour leader in 2015 after decades spent on the left-wing fringes of the party, Corbyn has repeatedly faced accusations of turning a blind eye to anti-Semitism in the party and among groups he supports.
The Board of Deputies of British Jews and the Jewish Leadership Council say Jeremy Corbyn's Labour Party has shown a "repeated institutional failure" to address anti-Jewish prejudice.
In an open letter, they said that "again and again, Jeremy Corbyn has sided with anti-Semites rather than Jews."
The groups plan to protest outside Parliament on Monday before a meeting with Labour lawmakers.
Allegations of Labour anti-Semitism have grown since pro-Palestinian socialist Jeremy Corbyn was elected leader of Britain's main opposition party in 2015.
Some in the party say Corbyn, a longtime critic of Israeli actions against the Palestinians, has allowed abuse to go unchecked.
The latest furor erupted over a six-year-old Facebook post by Corbyn supporting the artist behind a street mural that included anti-Semitic stereotypes.
It came to light that in 2012 Corbyn questioned a decision by London local authorities to remove the mural depicting men in suits with big noses playing Monopoly on the backs of naked people.
Corbyn has said he regrets not looking closely at the "deeply disturbing and anti-Semitic" mural before offering support to the artist.
Corbyn said in a statement he recognized anti-Semitism had occurred "in pockets within the Labour Party" and apologized for the pain this had caused. He condemned anti-Semitism and vowed to stamp it out of Labour politics.
In their open letter, the Jewish groups accused Corbyn of issuing "empty statements" while doing nothing to understand or tackle anti-Semitism. They said he was the figurehead of an anti-Semitic culture based on conspiracy theories and obsessive hatred of Israel.
"We conclude that he cannot seriously contemplate anti-Semitism, because he is so ideologically fixed within a far-left worldview that is instinctively hostile to mainstream Jewish communities," they said.
Several Labour members of parliament said they would join the protest on Monday, exposing internal divisions within Labour that had been papered over after Corbyn led the party to a stronger-than-expected showing in a general election last June.
Corbyn won the Labour leadership thanks to fervent support from many grassroots members who rejected the centrist approach of predecessors such as former Prime Minister Tony Blair, but many Labour lawmakers have been uncomfortable with his leadership.
The mural issue, like several similar controversies in the past, appeared not to dent Corbyn's support among dedicated grassroots followers who saw it as the latest attempt by establishment figures to smear and undermine him.
Some of them posted supportive messages on Twitter under the hashtag #PredictTheNextCorbynSmear.
Stephen Pollard, editor of the Jewish Chronicle newspaper, posted in response: "I'll have a go. It will be an accurate quote of something Corbyn has said."