The founder of the Palestine Live Facebook group – which contains Holocaust denial, and conspiracy theories about Israel’s involvement in the 9/11 and 7/7 terror attacks - is one of over 200 Jewish members and supporters of the Labour Party to sign a letter in support of Jeremy Corbyn.

The letter in the Guardian was signed by Elleanne Green, who has said it was a "badge of honour" to be under investigation by Labour over the Holocaust denial and antisemitism that her Facebook group contained, and urged anyone seeking "an end to bigotry and racism" to back Labour and Mr Corbyn.

In the letter, which was published on Wednesday, Ms Green, alongside several of prominent anti-Israel activists, criticised the “anti-Corbyn MPs” who left the Labour Party this week citing its problem with antisemitism.

Signatories said they believe that the Labour Party “under the progressive leadership of Jeremy Corbyn is a crucial ally in the fight against bigotry”.

The supporters also claimed Mr Corbyn’s “lifetime record of campaigning for equality and human rights, including consistent support for initiatives against antisemitism, is formidable”.

Mr Corbyn was found to have become a member of Ms Green's Palestine Live Facebook group in 2014 and left shortly after being elected Labour leader in 2015. Other members of the group included Shoah denier Paul Eisen.

At the time, Labour Party officers said they found Ms Green’s response to being under investigation “particularly troubling” and said she showed a “lack of interest in responding to these allegations”.

Other signatories of the letter include Mike Cushman, who has said "the Labour Party has become a pawn of Zionist organisations" and suggested that "most senior members of both main parties" other than Mr Corbyn and his allies are "part of the network of Israeli influence".

Mark Elf, whose name also appears on the letter in support of  Mr Corbyn, once wrote that "many, maybe most, Jews" have a "propensity for sheer instinctive dishonesty".

Mr Elf has said that Jewish communities have a "grotesque culture of deceit".

His name appears alongside Jenny Manson, chair of the controversial Jewish Voice for Labour group, which has routinely rejected or downplayed the party’s problem with antisemitism.

Ms Manson has said that she has not seen evidence of antisemitism in the Labour Party and defended Ken Livingstone's claim that Hitler "supported Zionism".

She has called for "much more freedom of speech than we are currently having on the subject of Israel and the Jews.”

Another signatory of the letter was Professor Jonathan Rosenhead, a leading JVL figure, who suggested antisemitic social media posts by Mr Corbyn supporters were the product of an Israeli government "false flag operation."

Professor Rosenhead has also been condemned by Holocaust historians for claiming “the Zionists” prevented hundreds of thousands of Jews escaping the Shoah.

The claim, made by Professor Rosenhead, was described by historians as “baseless” and “a fantasy”.

Naomi Wimborne-Idrissi, the co-founder of Jewish Voice for Labour, also signed the letter supporting Mr Corbyn.

Ms Wimborne-Idrissi has also defended Mr Livingstone’s comments about  Hitler and Zionism.

She has said that "Jews have to take responsibility" for Israel being a "racist endeavour".

JVL’s co-chair Leah Levane, who also goes under the name D’vorah Leah, was another signatory of the letter. 

Ms Levane supported Ms Green when she was revealed to be the founder of the Palestine Live Facebook group.

Another signatory was Glyn Secker, the JVL secretary.

Mr Secker has described the Board of Deputies and Jewish Leadership Council as acting in the service of Israel and protesting about antisemitism because they were “baying for a political lynching” – a reference to the suspended Labour and Momentum activist Jackie Walker.

He has leant his support to Ms Walker, who has been suspended for more than two years after saying she could not find a definition of antisemitism she could "work with".

Mr Secker has said: “We stand alongside Jackie Walker.”

Mr Secker was readmitted to the Labour Party after he was suspended over his membership Mr Green’s Facebook group in which antisemitic material was posted.

Dave Rich, who is the deputy communications director of the Community Security Trust, criticised the letter on Twitter.

Of the signatories he said: “These people are members of the Labour Party. They all insist that there is no antisemitism of significance in the party, and there are plenty of people, including in the leadership, who are happy to listen to them. And that's the problem.”