The Campaign Against Antisemitism (CAA) has referred the party to the Equality and Human Rights Commission and made a complaint to Labour about comments by Corbyn and his hosting of a Holocaust Memorial Day event in 2010 at which speakers reportedly compared the actions of Israel in Gaza to the Nazis.
The Labour leader acknowledged that he had appeared alongside people “whose views I completely reject” and apologised for the “concerns and anxiety” that caused.
He said: “The main speaker at this Holocaust Memorial Day meeting, part of a tour entitled ‘never again – for anyone’, was a Jewish Auschwitz survivor. Views were expressed at the meeting which I do not accept or condone.
“In the past, in pursuit of justice for the Palestinian people and peace in Israel/Palestine, I have on occasion appeared on platforms with people whose views I completely reject. I apologise for the concerns and anxiety that this has caused.”
Labour MP John Mann told BBC Radio 4′s Today programme Corbyn’s decision to host the event “breaches any form of normal decency”.
The CAA’s letter to the equality watchdog said: “We charge that the party has, through years of deliberate or reckless dereliction of its duty to enforce its own rules, created an atmosphere in which Jewish members and/or associates are discriminated against.”
The organisation also issued a fresh complaint – its third – about Corbyn to Labour.
As well as the 2010 Holocaust Memorial Day event it seized on comments made by Corbyn in 2012 when appearing on Press TV, the Iranian state-owned broadcaster, in which he linked a massacre of 16 Egyptian policeman to Israel.
Gideon Falter, chairman of the CAA, said: “The evidence shows beyond all doubt that Jeremy Corbyn is an anti-Semite and the Labour Party has become institutionally anti-Semitic.
“The problem is not one man but an entire movement which has hijacked the anti-racist Labour Party of old and corrupted it with a racist rot.”
A Labour Party spokesman said: “Labour is committed to rooting out anti-Semitism from our party and society. False and partisan attacks like this undermine the fight against anti-Semitism.”
One aspect of the CAA’s complaint was the party’s refusal to fully adopt the International Holocaust Remembrance Alliance (IHRA) definition of anti-Semitism, including its examples.
The party spokesman said: “Labour has adopted the IHRA definition, which is reproduced word for word in our code of conduct, and the examples are expanded on and contextualised to produce legally robust guidelines that a political party can apply to disciplinary cases.
“IHRA says its text is not legally binding and therefore there is no basis to legally challenge the code of conduct.”
An Equality and Human Rights Commission spokesman said: “We have received the complaint and will consider it to see what, if any, action is needed.”
Shadow chancellor John McDonnell said he wanted the party’s approach on anti-Semitism to be resolved soon.
“I thought we had got to a position where we are able to move on – we’re not – we’ve got to resolve that by September,” he told the Independent.
“The discussion is taking place, I think, that will enable that to happen.”
The CAA’s actions came as a member of Labour Party’s ruling body apologised for offensive comments about Jews.
Peter Willsman called some members of the Jewish community “Trump fanatics” and suggested they were “making up” problems about anti-Semitism in the party.
He subsequently apologised, acknowledging the “offensive nature of my comments”, and has referred himself for equalities training.
Willsman, who is standing for re-election to the National Executive Committee, said: “I recognise the offensive nature of my comments and that, in diminishing the experiences of those who face anti-Semitism in our party and society, I showed a lack of the sensitivity required for discussions around racism.”