Jeremy Corbyn, former leader of the UK's main opposition, has been told he can't represent the party as an MP after "undermining" its bid to tackle anti-Semitism.
Current Labour leader Sir Keir Starmer said he made the decision over his predecessor's reaction to a recent report on alleged anti-Semitism in the party.
The Equality and Human Rights Commission (EHRC) said there was "a culture within the party which, at best, did not do enough to prevent anti-Semitism and, at worst, could be seen to accept it".
In his initial response to the report, Corbyn admitted there was a problem with anti-Semitism in the party but claimed it had been overstated.
"Jeremy Corbyn’s actions in response to the EHRC report undermined and set back our work in restoring trust and confidence in the Labour Party’s ability to tackle antisemitism," said Starmer in a tweet on Wednesday.
"In those circumstances, I have taken the decision not to restore the whip to Jeremy Corbyn. I will keep this situation under review."
Margaret Hodge, a former Labour minister in the 2000s and a leading member of the Jewish Labour Movement, responded to Starmer's announcement on Twitter to say that "withholding the whip is the right decision".
The London MP described Labour's internal complaints system as "broken and unjust", adding that it had "caused untold hurt and anguish across the Jewish community" and made her question her place in the party.
Starmer's move to exclude Corbyn was also welcomed by the Board of Deputies of British Jews, which describes itself as "the voice of the British Jewish community". Calling the former opposition lader's stance on anti-Semitism "shameless and remorseless", the board said "'zero tolerance' must mean precisely that, whether for antisemites or their apologists".
But supporters of the former opposition leader sprang to his defence. Ex-shadow chancellor (finance minister), John McDonnell said the move to deprive him of the party whip in parliament was "just plain wrong and will cause more division and disunity in the party".
The tussle within Labour reflects the long-standing division of power, and frequent tensions, between the party's MPs and its wider membership.
Corbyn's suspension was lifted earlier this week by a disciplinary panel on the party's governing body, the National Executive Committee (NEC), after the former leader clarified his earlier comments to say that the problem of anti-Semitism had not been exaggerated.
In response to his readmission, Corbyn said: "I am pleased to have been reinstated in the Labour Party and would like to thank party members, trade unionists and all who have offered solidarity.
"Our movement must now come together to oppose and defeat this deeply damaging Conservative government."
Jeremy Corbyn, a veteran left-winger in the party, had been an MP for over three decades when he was elected Labour leader in 2015 on a wave of support from new members in particular.
But he did not attract the same enthusiasm among the public at large and in December 2019 led the party to its worst general election defeat since 1935.