Jeremy Corbyn has been accused of lying about Labour’s attempts to investigate antisemitism in a row that left the party in disarray after the first television debate of the General Election campaign.

Jewish Labour Movement (JLM) national secretary Peter Mason reacted furiously to the Labour leader’s claim, made in Tuesday night’s live ITV debate with Boris Johnson - that his party had “investigated every single case” of anti-Jewish racism.

Mr Mason, a councillor in Ealing, west London, wrote on Twitter: “This is a lie.”

As the debate came to an end on Tuesday evening, furious Mr Mason revealed on social media that there were 130 cases of alleged antisemitism from Labour members that were unresolved, after being passed to the party’s highest disciplinary body for a decision on what action to take.

Mr Mason also revealed his organisation submitted evidence of “thousands” of unresolved examples of alleged Jew-hate to the equalities watchdog the Equalities and Human Rights Commission as part of the watchdog's investigation into allegations Labour is “institutionally antisemitic.”

During Tuesday’s televised debate, Mr Corbyn had been asked by presenter Julie Etchingham about a statement by the Board of Deputies that Labour had turned into “a cesspit of antisemitism”.

Mr Corbyn said: “I have taken action in my party. When anyone has committed any antisemitic acts or made any antisemitic statements they are either suspended or expelled from the party and we have investigated every single case.

"We do take this very, very seriously indeed because I do not want to live in a society where racism is rife.”

But Mr Mason accused Mr Corbyn of misleading the public, saying: “There are at least 130 outstanding antisemitism cases, some dating back years, that still haven’t been dealt with.

"The party haven’t bothered to investigate the cases properly or make decisions. This is the tip of the iceberg.

"Corbyn and Labour’s total failure to deal with antisemites has seen it be investigated by the EHRC for institutional anti-Jewish racism. They don’t launch major investigations without cause, and the investigation continues through the election."

The JLM national chair also revealed he had submitted a dossier of cases to the EHRC on Tuesday based on the sworn testimony of more than 70 Labour activists, officers, staff and politicians.

He added: "Each of them desperately worried about the turn the party has taken to foster and embed a rancid and abusive, victim blaming culture, one which is then denied, obfuscated and diminished by the leadership, and who want to put the situation right."

The councillor went on: "We have submitted details to the EHRC of thousands of cases left unresolved. Cases where grossly antisemitic behaviour was excused, and details of the worst political manipulation of a system by those running the party.

"And all for what? How has this festering anti-Jewish racism, the inaction, the lies & the cover ups, ever helped the party in any way? This is a disgraceful episode in the long and proud history of the Labour Party. He should be ashamed of himself.”

Appearing on Sky News on Wednesday, Labour’s Dawn Butler, the shadow equalities minister, was asked if Mr Corbyn was right to say what he did in the TV debate.

She said: “If Jeremy Corbyn has been informed by the General Secretary that all the cases have been dealt with in some may then absolutely he is right to say that is the case – because that is what he has been informed.”

Neil Coyle, the Labour candidate for Bermondsey and Old Southwark and a long-time critic of Mr Corbyn’s failure to deal with the issue, told the JC: “Anyone who thinks antisemitism has been dealt with in the Labour Party is simply not listening.”

He added: “We have lost Jewish MPs, members and voters over the failure to properly address the problem.

"Louise Ellman left the party after the complaints process was tinkered with and due to unacceptable delays and insufficient severity of punishment measures.

“I am hugely sorry that UK politics’ greatest force for tackling racism has still not been able to tackle this fully.”

Karen Pollock, from the Holocaust Educational Trust, said that it was “blatantly untrue” for the Labour leader to claim the problem was being effectively tackled.

During the debate, Boris Johnson had accused Mr Corbyn of a “complete failure of leadership over antisemitism”. 

However the prime minister then switched the subject to Brexit, continuing: “But the failure of leadership is even worse when you look at what is happening on their Brexit policy.”