Luciana Berger, who is Jewish, quit the party in February 2019, saying she could not "remain in a party that I have today come to the sickening conclusion is institutionally antisemitic".

But Labour Leader Sir Keir Starmer revealed Ms Berger, the Liverpool Wavertree MP from 2010 to 2019, had accepted his invitation to rejoin Labour.

"My test for change was whether those who were rightly appalled by how far we had fallen believe this is their party again," he tweeted.

"I know we've more to do but we're unrecognisable from the party that forced her out."

Sir Keir shared images of the letter he had sent to Ms Berger apologising to her "again on behalf of the whole party" for the "disgusting" antisemitic abuse she received while Mr Corbyn was leader.

He said she had been "forced out by intimidation, thuggery and racism" in a "stain on Labour's history" and invited her back to the party.

Ms Berger lost her seat after joining the fledgling party Change UK, then later the Liberal Democrats.

In her reply to Sir Keir, Ms Berger said: "I am looking forward to rejoining the party and working with you to continue what you have started.

"It is time to replace this reckless and divisive government and ultimately make the difference our country so desperately deserves."

Labour 'fell into the depths of the abyss' under Corbyn

Ms Berger said she was "pleased" with the Equality and Human Rights Commission's decision to no longer monitor the party over antisemitism, but added: "As you [Sir Keir] have rightly said, this is not a moment for celebration and there is a great deal more to do."

She claimed the party "fell into the depths of the abyss under Jeremy Corbyn's reign".

"I never expected to bear witness to the volume and toxicity of anti-Jewish racism espoused by people who had been allowed to join Labour, and to experience a leadership that treated antisemitism within the party's ranks differently to every other kind of racism - and that by refusing to condemn it, encouraged it," she said.

"But that is exactly what happened."

Sir Keir wrote: "Before you were forced out of the party, you were an outstanding Member of Parliament."

He said the party and British politics are "poorer places" without her, and apologised to her for the "intolerable and unacceptable" experience she had.

"The abuse you suffered was disgusting. You were left isolated and exposed. Shamefully, those who should have defended you stood by.

"The Labour Party - our party - has always prided itself on being a party of equality, collectivism, solidarity and anti-racism.

"But during those dark days we were none of those things."

Her return was applauded by several from the party hierarchy, including shadow chancellor Rachel Reeves who tweeted: "So pleased to have you back, Luciana."

Peter Kyle, the party's Northern Ireland spokesman, tweeted: "An emotional and healing moment. The Labour Party and Luciana…friends finally reunited. I'm grateful to @Keir_Starmer for making this possible, and in awe of @lucianaberger's strength and compassion for giving us this precious second chance. Labour has changed for the better."

Margaret Hodge, another of Labour's critics of Mr Corbyn, said on Twitter: "Welcome back Luciana! It's so important that those who were pushed out of the Labour Party because of vile antisemitism now feel able to return to their political home. We've come so far. Labour is proudly an outward looking, tolerant & inclusive party once again."

Jewish Labour Movement added: "Our former Parliamentary Chair @lucianaberger is a hero of the Labour Movement. What happened to her under Corbyn's leadership was a disgrace and she showed immense bravery. That she feels now is the time to rejoin shows the party is on the right track."

Starmer rules out Corbyn standing for Labour at next election

Marking the EHRC's decision to no longer monitor the party for antisemitism, Sir Keir ruled out allowing Jeremy Corbyn to stand as a Labour candidate in the next general election.

The human rights watchdog in 2020 found the party broke equality law over its handling of antisemitic complaints.

Mr Corbyn rejected some of the report's findings and claimed the issue had been "dramatically overstated for political reasons" - comments which led to Labour's headquarters suspending him from the party.

Ms Berger joined the board of online used-car retailer Cazoo in August 2021 as chair of its environmental, social and governance (ESG) committee.