Jackie Walker, vice-chair of the hard-left Momentum activist group, is understood to have been suspended by Labour following comments she made about Holocaust Memorial Day.
The party does not comment on individual members or their status within the party, but news of Ms Walker’s apparent removal came late on Friday evening.
It is the second time this year that the activist and ally of Jeremy Corbyn has been suspended by Labour.
It had been revealed on Thursday that she is likely to be removed from her position with Momentum at a meeting of the group’s steering committee. That session is due to take place tomorrow.
A Momentum spokesman had told the Guardian senior members of the group were seeking to have her moved from her senior role.
In last Monday’s Jewish Labour Movement training session on tackling antisemitism, which took place at the party conference in Liverpool, Ms Walker criticised Holocaust Memorial Day, claiming it should remember genocides other than the Shoah - which it does.
She was told that the annual memorial did recognise other episodes of mass murder, but Ms Walker went on to claim she had not seen a definition of Jew-hate which she could “work with”.
Ms Walker had later claimed footage from the training session was leaked “with malicious intent” and repeatedly denied she was antisemitic.
Board of Deputies Vice President Marie van der Zyl said: “We welcome the removal of Jackie Walker as Vice Chair of Momentum as well as her suspension from the Labour Party. It is a clear acknowledgement that her comments about Holocaust Memorial Day and antisemitism were crass, ignorant and wholly unacceptable. Antisemitism is a real, substantial problem in UK politics. Any suggestion that it is somehow an exaggerated or 'weaponised' issue is therefore deeply offensive. We call on the Labour Party to expel her once and for all.”