Seventy serving and ex-Labour officials have given sworn statements to an official investigation in to Labour’s handling of anti-Semitism allegations.
The statements form part of a submission – seen by the BBC – from the Jewish Labour Movement to the Equality and Human Rights Commission (EHRC).
The commission announced a formal investigation earlier this year.
Labour said it was committed to rooting out anti-Semitism in the party and the country.
The Jewish Labour Movement is asking the EHRC to urge the Labour Party to acknowledge it has become “institutionally anti-Semitic” and needs to change.
The EHRC declined to comment, saying its investigation was “live and ongoing”.
The Jewish Labour Movement has been affiliated to the party for a century and represents about 2,500 members.
It asked the EHRC to look in to Labour’s handling of anti-Semitism allegations – and its submission argues that anti-Semitic conduct has become “pervasive” in recent years.
It suggests there are no reliable figures for how many cases of anti-Semitism still have to be dealt with by the party’s complaints team, despite the Labour leadership arguing processes had been speeded-up.
The Jewish Labour Movement is claiming that 136 complaints were outstanding in October while around 100 allegations were not logged in the system at all.
Labour say these figures are inaccurate but have not provided any official statistics on the issue since July.
The Jewish Labour Movement’s submission includes a signed affidavit from a former Labour official who alleges they were asked to transfer details of complaints being investigated at Labour’s headquarters to the party leader’s office.
A Labour spokesman said the party is not institutionally anti-Semitic and it was the only party to have published any figures on cases.
He added that under the party’s new procedures there would be more rapid expulsions – and Labour was co-operating with the EHRC.