Labour has sought to distance himself from a series of pro-Jeremy Corbyn Facebook groups that have anti-Semitic, racist and abusive comments.
A report published in the Sunday Times claims to have discovered more than 2,000 messages.
A Labour spokesman said that the groups are not connected to the party in any way.
Recently appointed as a member of Labour’s ruling body, the comedian Eddie Izzard, he said the party should “to completely eradicate the stain of anti-Semitism”.
The report is the result of two months of investigation by the Sunday Times in the 20 largest pro-Corbyn Facebook groups.
Among the messages was praised by Adolf Hitler and the death threats of the Prime Minister, Theresa May, said the journal.
Meanwhile, one of the largest Work from private donors, has told the Observer that he left the party over their inability to deal with “the most blatant acts of anti-Semitism”.
Sir David Garrard, who has donated £1.5 million to Labour since 2003, told the newspaper: “I have seen with dismay and foreboding of the manner in which the leadership has, in my opinion, in the past two years, completed in itself.”
There is No truce for the Job
Jonathan Blake, political correspondent of the BBC
With the negative stories on the front pages of at least four newspapers, this is not a happy Easter Sunday of the workforce.
The on-line abuse highlighted by the Sunday Times investigation shows a problem that the party has a relatively small number of people willing to use racism, misogyny and threats of violence in support of Jeremy Corbyn.
The job has denounced the behavior and distanced themselves from the groups.
Mr Corbyn has condemned, criticized, and apologized time and time again.
But after a bad week for the party, things have not improved.
The leader has admitted that the Work must “do better” in the fight against anti-Semitism, but with no apparent quick solution to hand and do not let the accusations, he has a way to go to convince everyone in his party that he has a control over the problem.
The Sunday Times says that the Facebook groups covered in its report have a membership of around 400,000 people, including 12 senior staff working for the Lord Corbyn and the shadow chancellor John McDonnell.
Comments in the groups show members that incite to violence, the report says.
He also said that he found messages from the comparison of Conservatives to Nazis and suggesting a journalist should be assassinated.
Writing in the newspaper, Jewish labour MP Luciana Berger said she had received an email from someone who claimed to be a member of the party saying that she should kill herself.
She also had been called “Judas”, “a venal piece of detritus”, a “Zionazi” and an “absolute parasite.”
A spokesman for the Labour Party, said: “These groups are not run by the Labour Party or connected to the party in any way.”
The work also told the Sunday Times that no one in the Lord Corbyn or Mr McDonnell’s office has been seen, published or approved anti-Semitic or abusive messages.
The BBC understands that Mr Corbyn has already removed your personal Facebook account, despite their Facebook Page, a separate type of account for public figures and organizations, remains active.
The latest allegations mark a deepening row over anti-Semitism in the Labour Party, which has dogged Mr Corbyn of the week.
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How to Work anti-Semitism saga unfolded
Jeremy Corbyn and Work of the anti-Semitism problem
Broke out when Mr Corbyn himself was criticized by the opposition to the removal of an anti-Semitic mural in east London in 2012.
On Saturday, senior Labor officer Christine Shawcroft resigned to the part of the governing body, the National Executive Committee, and was replaced by comedian Eddie Izzard.
Had surfaced that she had opposed to the suspension of a council candidate accused of denying the Holocaust.
In a statement Mr Izzard said: “Despite the fact that this is not the way that I had hoped to join the NEC I have the honor to step up and represent the Work of the members at the heart of our party.”
On the anti-Semitism of the row said Labour “should amend and repair the damage with the Jewish community as Jeremy Corbyn has promised to do.”
On Friday, Mr Corbyn admitted to Work must “do better” through its handling of anti-Semitism.