A five-strong panel made up of members of the National Executive Committee decided to allow him back into the party – plunging Sir Keir Starmer into a fresh crisis over the controversy that dogged Labour for so long.
The Labour leader is wrestling with the further headache of whether to restore the whip to Mr Corbyn, allowing him to sit as a Labour MP, a separate decision certain to inflame one wing of the party or the other.
The restoring of party membership came after the former party leader released a conciliatory statement, saying concerns over antisemitism within Labour are “neither exaggerated nor overstated”.
However, the decision to readmit Mr Corbyn – after just 19 days out in the cold – was immediately condemned by Jewish groups and some furious Labour MPs.
Margaret Hodge, one of the Jewish Labour MPs who suffered abuse and threats from what appeared to be Mr Corbyn’s supporters, attacked “a broken outcome from a broken system”.
“A factional, opaque and dysfunctional complaints process could never reach a fair conclusion. This is exactly why the EHRC instructed Labour to set up an independent process!”
The Board of Deputies of British Jews condemned what it called Mr Corbyn’s “pathetic non-apology”, urging Sir Keir to put it in the “dustbin of history”.
And Mike Gapes, one of the Labour MPs who quit the party last year over Mr Corbyn’s leadership, said: “This has now become a defining watershed for Keir Starmer and the future of the Labour Party.”
Sir Keir, the new Labour leader, had always insisted Mr Corbyn’s disciplinary process would be conducted by officials, not the head of the party.
However, Sir Keir is now facing a backlash from his own supporters on the Labour benches, who were delighted when he appeared to draw a line under the tainted Corbyn years.
This evening, he tweeted: “I know that this has been another painful day for the Jewish community and those Labour members who have fought so hard to tackle antisemitism. I know the hurt that has been caused and the trauma people have felt.
“Jeremy Corbyn’s statement in response to the EHRC report was wrong and completely distracted from a report that identified unlawful conduct in our tackling of racism within the Labour Party. This should shame us all.
“I will not allow a focus on one individual to prevent us from doing the vital work of tackling antisemitism. When I stood as leader of the Labour Party, I was clear that my first priority would be to root out antisemitism. It still is.
”I know we have a long way to go, but I am absolutely resolute in my determination to make the Labour Party a safe place for Jewish people. I stand by the commitments I made last month to accept the findings and the recommendations of the EHRC’s report in full.
“That must mean establishing an independent complaints process as soon as possible in the new year. This is my commitment and my promise to our party, the Jewish community and the British people.”
It is understood no decision has been taken on whether to restore the Labour whip to the former leader.
Last month, the long-awaited Equality and Human Rights Commission (EHRC) report found that Labour broke the law by failing to prevent “acts of harassment and discrimination” against Jewish people.
In its damning judgement, it said Mr Corbyn’s leadership “did not do enough to prevent antisemitism and, at worst, could be seen to accept it.”
But, within minutes, the former leader blamed “an obstructive party bureaucracy” for stalling his attempts at reform, saying: “I do not accept all of its findings”.
In a statement that enraged Sir Keir, he wrote: “The scale of the problem was also dramatically overstated for political reasons by our opponents inside and outside the party, as well as by much of the media.”
In the fresh statement, issued early on Tuesday, Mr Corbyn said: “We must never tolerate antisemitism or belittle concerns about it.
“To be clear, concerns about antisemitism are neither ‘exaggerated’ nor ‘overstated’. The point I wished to make was that the vast majority of Labour Party members were and remain committed anti-racists deeply opposed to antisemitism.”
Fiona Sharpe, of Labour Against Antisemitism, said: “The lifting of Jeremy Corbyn’s suspension from the Labour Party, following his non-apology, serves only to further highlight the issues raised in the EHRC report.”
But the leftwing MP Lloyd Russell-Moyle tweeted: “Very pleased indeed that @jeremycorbyn has been unsuspended from the party. We must go forward united and expose the failures of this government”
Sir Keir has been given until 10 December to draft an action plan to implement the EHRC’s recommendations, having announced he will accept them all.
It identified three breaches of the 2010 Equality Act relating to “political interference in antisemitism complaints”, a “failure to provide adequate training to those handling antisemitism complaints” and “harassment”.
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