Ken Livingstone, the former Mayor of London, has been suspended from the Labour Party following a series of interviews in which he claimed that Adolf Hitler supported Zionism.
Dozens of the party’s MPs had called for Mr Livingstone to be suspended or ejected after a round of media appearances this morning.
In a statement issued at 1.25pm, the party said: “Ken Livingstone has been suspended by the Labour Party, pending an investigation, for bringing the Party into disrepute.
“The Chief Whip has summoned John Mann MP to discuss his conduct."
During a visit to Hull, Labour leader Jeremy Corbyn said: "He has been suspended from the party. We are not tolerating antisemitism in any form whatsoever in our party."
Mr Corbyn denied his party was facing an antisemitism "crisis". Speaking later on the BBC he said: "I suspect much of this criticism about a 'crisis' comes from those who are nervous of the party at local level."
Mr Mann, the Labour MP for Bassetlaw, had earlier clashed with Mr Livingstone, accusing him of being “a Nazi apologist”.
Labour later said Chief Whip Rosie Winterton had met Mr Mann and had made it "absolutely clear" that the spat, on television, was "completely inappropriate".
The furore began during an interview on Vanessa Feltz BBC Radio London show to discuss the suspension of Naz Shah over her antisemitic social media posts .
Mr Livingstone claimed the Nazi dictator had initially backed moving Jews to Israel “before he went mad”.
The former MP later repeated the same claims during an appearance on the BBC Daily Politics show.
He had earlier claimed: “There has been a very well-orchestrated campaign by the Israel lobby to smear anybody who criticises Israeli policy as antisemitic. I had to put up with 35 years of this, being denounced.”
Mr Livingstone, 70 and a two-time Mayor of London, said he believed it was "over the top" to "think of antisemitism and racism as exactly the same thing".
The series of remarks brought a furious reaction from Jewish groups, the Israeli ambassador to Britain and dozens of Labour MPs.
Board of Deputies president Jonathan Arkush said: “Ken Livingston’s comments were abhorrent and beyond disgraceful.
"His latest comments combine Holocaust revisionism with antisemitism denial, when the evidence is there for all to see. He lacks any sense of decency.”
Israeli ambassador Mark Regev tweeted: “Not sure which is worse, deliberately distorting Hitler’s goals or accusing his Jewish victims of being his partners. #BothareantiSemitism.”
Jon Lansman, founder of the pro-Corbyn Momentum movement, told the JC: “My view is that Ken has said increasingly silly thinks about antisemitism, Zionism, racism. I think it is very sad what is happening.
“All political careers end in failure and I think he should have the sense to exit.”
Joan Ryan MP, chair of Labour Friends of Israel, had earlier said: “To speak of Zionism – the right of the Jewish people to self-determination – and Hitler in the same sentence is quite breathtaking.
"I am appalled that Ken Livingstone has chosen to do so. There cannot be one rule for some Labour party members and one rule for others. He should be suspended from the Labour Party immediately.”
Labour MPs including Sadiq Khan, Wes Streeting, Liz Kendall and Angela Smith had urged the party to act.
Director of external affairs for the Jewish Leadership Council, Bernard Hughes said: “We do not believe the Labour Party is institutionally racist or antisemitic but sadly there are individuals within the party whose views and statements are antisemitic and have really shocked us.
"The party leadership must now act decisively. The JLC will continue to give very strong support to efforts by CST and the All Party Parliamentary Group Against Antisemitism to combat this terrible issue.
"We have supported the request by the Jewish Labour Movement to have Ken Livingstone suspended from Labour for the offensive remarks he made this morning.”
The Senior Rabbi of Liberal Judaism, Rabbi Danny Rich said, as a long-term member of the Labour Party, "I am certainly not someone who Ken Livingstone can write off as one of his 'usual critics'.
"But today, like Jews and people of all faiths, I was disgusted by his comments as he toured radio and TV stations.
"If anyone has gone mad, it is Ken Livingstone. His comments get more offensive and unworthy every time he is interviewed.
"Suspending him from the Labour Party is not the end of the matter. Livingstone is a symptom, not the cause.
"I am nervous that by focussing on one large personality, we are not dealing with the issues which lead him to make such a statement."
Bicom chief executive James Sorene said: "Recent comments about Israel and Zionists by members of the Labour party, and the way some have defended them, show a fundamental misunderstanding of what Zionism is.
“Anti-Zionists deny the Jewish people their right to national self-determination, seek to portray the very existence of Israel as a crime and indulge dangerous fantasies about the country no longer existing.
"Criticism of the Israeli government is of course entirely legitimate, as it is against any government. But when that criticism is expressed in violent language, directed at its people in racist terms or uses references to Hitler and Nazism, it is antisemitic and deeply offensive.
"If the only country in the world that you want to disappear is the Jewish one then you are in very bad company, on the wrong side of history."