LONDON—British Jews, who accuse Labour Party leader Jeremy Corbyn of “siding with anti-Semites rather than with Jews,’’ have been called to rally on Monday in Parliament Square in London as Labour Parliament members meet inside.

Labour Party leader Jeremy Corbyn said he backed the painting of a mural containing antisemitic imagery on the grounds of free speech. The graphic, Freedom for Humanity, was painted six years ago on a property near Brick Lane in London’s East End by renowned international graffiti artist Kalen Ockerman.

It depicted a group of Jewish businessmen and bankers sitting around a Monopoly-style board, counting money. The artwork was painted on the end wall of a private property, but was removed by local authorities after complaints from residents.

At the time, Corbyn offered support to Ockerman.

The Board of Deputies of British Jews and the Jewish Leadership Council urged supporters to stage a show of solidarity London under the banner “Enough is Enough” outside parliament on Monday as Labour MPs hold their weekly meeting, following the latest row over anti-Semitism in the party.

In the meantime, Corbyn expressed regret for his support for the creator of the anti-Semitic mural.

In a strongly worded letter, British Jewish leaders claim the mural row was just the latest evidence that the Labour leader “cannot seriously contemplate anti-Semitism because he is so ideologically fixed within a far-left worldview that is instinctively hostile to mainstream Jewish communities.”

“Again and again, Jeremy Corbyn has sided with anti-Semites rather than Jews. At best, this derives from the far-left’s obsessive hatred of Zionism, Zionists and Israel. At worst, it suggests a conspiratorial worldview in which mainstream Jewish communities are believed to be a hostile entity, a class enemy,” said Jonathan Arkush, president of the Board of Deputies of British Jews and Jonathan Goldstein, chairman of the Jewish Leadership Council. They also mentioned  Corbyn’s friendship with Hezbollah and Hamas, and his opposition to the extradition of controversial Muslim cleric Raed Salah.

The letter begins: “We’ve had enough of hearing Jeremy Corbyn ‘opposes anti-Semitism,’ whilst the mainstream majority of British Jews, and their concerns, are ignored by him and those he leads.”

The Jewish leaders denounced an “institutional failure to properly address Jewish concerns and to tackle anti-Semitism,” citing the Chakrabarti report as a “glaring” example.

Corbyn issued his own statement,  noting that he was “sincerely sorry for the pain which has been caused” by what he called “pockets of anti-Semitism.”

“Our party has deep roots in the Jewish community and is actively engaged with Jewish organisations across the country,” he said. “We are campaigning to increase support and confidence in Labour among Jewish people in the U.K.”

But Karen Pollock, chief executive of the Holocaust Educational Trust, said that Corbyn’s apology “might be too late.”

“When there were examples of Labour Party members saying ‘Jews kill and kidnap their way around the world’ or referring to the Holocaust Educational Trust as the ‘Holocaust Indoctrination Programme’ … was that not enough to make the leader of a Labour Party say it’s disgusting and this has to stop?”

In a statement, European Jewish Congress president Moshe Kantor expressed support for the Board of Deputies and the Jewish Leadership Council ahead of Monday’s the rally in London. “It has been abundantly clear for too long that the Labour leadership under Jeremy Corbyn has at best a massive blind spot when it comes to anti-Semitism,’’ he said, “and at worst openly encourages hatred and double-standards against Jews. Enough apologies, enough insipid justifications, enough excuses.’’