LONDON (AP) — 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.

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.

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 that Labour must show "total commitment to excising pockets of anti-Semitism that exist in and around our party." He said he would meet with Jewish leaders in the coming days.