Jeremy Corbyn has been asked by Labour's chief whip Nick Brown to apologise "unequivocally, unambiguously and without reservation" for his comments in response to the Equality and Human Rights Commission (EHRC) report into anti-Semitism in the party.
In a letter obtained by the PA news agency, Mr Brown said the former Labour leader’s response caused “distress and pain” to the Jewish community.
Mr Corbyn was suspended from the party last month for saying anti-Semitism in the party had been "dramatically overstated for political reasons".
He later attempted to clarify his comments in a statement to the party, saying concerns about anti-Semitism were “neither ‘exaggerated’ nor ‘overstated’”.
He was reinstated as a Labour member by the National Executive Committee following a meeting of a disciplinary panel three weeks later.
But Labour leader Sir Keir Starmer withheld the whip from him, describing his readmission as “another painful day for the Jewish community.
Mr Brown, writing to Mr Corbyn on Monday, said that to inform an investigation into whether the Islington North MP broke the party’s code of conduct he wanted him to consider apologising for his comments.
He wrote: “Will you unequivocally, unambiguously and without reservation apologise for your comments made on the morning of 29 October 2020, in particular for saying ‘One anti-Semite is one too many, but the scale of the problem was also dramatically overstated for political reasons by our opponents inside and outside the party, as well as by much of the media’, which caused such distress and pain to Jewish members of the Labour Party and the wider Jewish community?”
Mr Brown also asked Mr Corbyn to confirm that he will remove or edit his response – which he posted on Facebook, and asked for an assurance that he will cooperate fully with the party as it seeks to implement the EHRC’s recommendations.
A Labour spokesman said: "Following consultation with the Labour Leader, the Chief Whip has written to Jeremy Corbyn about his precautionary suspension from the whip.
"In the interests of transparency, a copy of this letter has been put in the public domain. We will not be making any further comments."
Last week, former Labour leader Gordon Brown suggested there could be a way back into the Parliamentary Labour Party (PLP) for Mr Corbyn, but "there's got to be an apology... Jeremy himself has got to say he got it wrong".