Jeremy Corbyn was called a "f****** racist and an antisemite" by one of his own Jewish MPs in an extraordinary Commons bust-up.
Dame Margaret Hodge, a former minister, reportedly told her party leader he did not want "people like me" in the party.
The furious row came after Labour adopted a new code of conduct that has been heavily criticised by Jewish community leaders and dozens of the party's own MPs.
Dame Margaret has previously spoken of having lost relatives in the Holocaust and has criticised the Labour leadership's approach to tackling anti-Jewish abuse in the party.
According to the Huffington Post, she confronted Mr Corbyn behind the Speaker's chair after crunch votes on Brexit on Tuesday night.
She is reported to have told him: "You're a f****** antisemite and a racist...You have proved you don't want people like me in the party."
The Labour leader is said to have replied: "I'm sorry you feel like that."
Senior Labour sources did not dispute reports of the exchange and suggested Mr Corbyn would be seeking a meeting with Dame Margaret to discuss the matter. She is also likely to be reported to Labour whips for the tirade.
It came after Labour's National Executive Committee (NEC) signed off on a contentious code of conduct that only partly adopts the internationally-recognised International Holocaust Remembrance Alliance (IHRA) definition of antisemitism.
The party has agreed to use the definition but has not directly adopted four of the IHRA examples of antisemitism. They are: accusing Jewish people of being more loyal to Israel than their home country, claiming the existence of Israel is a racist endeavour, holding Israel to higher standards than other countries, and comparing Israeli policies to those of the Nazis.
Labour has insisted the examples are covered elsewhere in the code of conduct, but Jewish community groups condemned the document.
Facing a growing backlash, the NEC admitted "serious concerns" had been raised and proposed ongoing consultation with Jewish groups.
A Labour Party spokesperson said: "The NEC upheld the adoption of the code of conduct on antisemitism, but in recognition of the serious concerns expressed, agreed to reopen the development of the code, in consultation with Jewish community organisations and groups, in order to better reflect their views."
That was not enough for many Labour MPs, who spoke out strongly against the NEC's decision. The party's MPs and peers had earlier voted overwhelmingly in favour of adopting the full IHRA definition.
Ed Miliband, the former Labour leader, wrote on Twitter: "Labour should adopt the full IHRA definition. The argument that it is somehow incompatible with criticising the actions of the Israeli government is wrong. The views of the vast majority of the Jewish community are very clear. I would urge the NEC to get on with this at speed."
Chuka Umunna, the Streatham MP, said: "It is deeply disappointing that despite this strong statement from MPs and an appeal from 68 rabbis from across the Jewish community, the NEC today has not committed to adopting the IHRA definition and examples in full, instead choosing to hold a review.
"The Jewish community has clearly been subject to differential treatment by our party these last few years which is discriminatory. Part of the reason I joined the party was because I thought it was anti-racist which is why this horrifies me."
Anna Turley, MP for Redcar, said: "It is extremely arrogant of Labour’s NEC to think it can or should devise a better definition of antisemitism than the IHRA. This is a community who have always faced persecution, know what it looks like and how it starts. This is utterly shameful."
Another MP, Ian Austin, said the decision was "utterly shameful" and made him "ashamed to be a member of the Labour Party."
He added: "Let's be really clear: Jeremy Corbyn and members of Labour's NEC who supported this appalling decision clearly do not care about the immense distress and offence that has been caused to Britain's Jewish community.
"They clearly think they know more about antisemitism than the chief rabbi, dozens of other rabbis, organisations representing the vast majority of British Jews, Jewish MPs and members."
Controversially, it says that even "contentious" comments about Israel will not be regarded as antisemitic "unless accompanied by specific antisemitic content".
The confirmation that the code will be adopted prompted a furious response from Jewish community groups.
In a joint statement, the Board of Deputies, Jewish Leadership Council and the Community Security Trust said: "The decision taken by the NEC today to adopt a watered-down definition of antisemitism will be regarded with a mixture of incredulity and outrage by the overwhelming majority of the UK's Jews."
"This is a sad day for the cause of anti-racism in this country. Labour, for so long a party that put equality and inclusion at the centre of its values, has today decided to claim that it understands antisemitism better than the victims of this vile prejudice and to set its face against the clear views of the Jewish community."
They added: "The NEC has chosen to disregard the views of the Jewish community, an unprecedented show of unity by rabbis from every part of the community and even its own parliamentarians.
"They have distorted and diluted the IHRA definition of antisemitism that is widely accepted and used by the Jewish community, the UK government, the Scottish Parliament, the Welsh Assembly, the Crown Prosecution Service, the police, and dozens of local authorities, to create their own weaker, flawed definition whose main purpose seems to be to protect those who are part of the problem."
The Jewish Labour Movement, meanwhile, claimed Labour had "acted in a deliberate and offensive reckless manner in believing it understands the needs of a minority community better than the community itself".
It came after the chief rabbi accused Labour of showing "unprecedented contempt" towards Jews, and 68 other rabbis penned an open letter accusing the Labour leadership of behaving in an "insulting and arrogant way".
Labour has insisted its code of conduct goes further than the IHRA definition.
A spokesperson said: "These are the most detailed and comprehensive guidelines on antisemitism adopted by any political party in this country.
"They adopt the IHRA definition and contextualise and add to the working examples to produce a practical code of conduct that a political party can apply in disciplinary cases."
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