KEIR Starmer’s decision to boot Jeremy Corbyn out of the Parliamentary Labour Party was denounced as “vindictive and vengeful” by a key ally of the former leader as a furious backlash among left-wingers was unleashed.

Mr Corbyn’s supporters claimed he could now take the new leadership to court to get the decision reversed on the grounds that it was made as a result of "political interference" in the disciplinary process.

While the London MP was reinstated as a party member on Tuesday following a meeting of a disciplinary panel of Labour’s ruling National Executive Committee, early on Wednesday the new leadership announced that the 71-year-old would not be readmitted to the parliamentary party at Westminster. This means he will sit as an independent MP.

In a statement, Sir Keir explained: “Jeremy Corbyn’s actions in response to the Equalities and Human Rights Commission[EHRC] report undermined and set back our work in restoring trust and confidence in the Labour Party’s ability to tackle anti-Semitism.

“In those circumstances, I have taken the decision not to restore the whip to Jeremy Corbyn. I will keep this situation under review.”

While the latter remark leaves the door ajar for Mr Corbyn to return, party sources suggested this might not happen for a number of years, possibly not even before the next General Election in 2024.

Last month, Mr Corbyn was suspended from Labour for his response to the EHRC report, which found the party had broken the law in its handling of anti-Semitism complaints.

He claimed the scale of anti-Semitism in the party had been “dramatically overstated for political reasons” by opponents inside and outside Labour, along with the media.

However, he later attempted to clarify his comments in a statement to the party, saying concerns about anti-Semitism were “neither ‘exaggerated’ nor ‘overstated’”.

The decision to exclude Mr Corbyn from the Parliamentary Labour Party was welcomed by Jewish campaigners but denounced by supporters of Mr Corbyn.

Some 27 MPs signed a statement from the Socialist Campaign group, branding Sir Keir’s decision “wrong and damaging” and demanding the decision be swiftly reversed.

It read: “The decision and division it causes severely undermines the efforts to unite to defeat anti-Semitism and fully implement the EHRC recommendations and to challenge and defeat this disastrous Conservative Government.”

John McDonnell, the former Shadow Chancellor and an ally of Mr Corbyn, said the leader’s action was “just plain wrong” and would cause “more division and disunity in the party”.

Diane Abbott, who served as Shadow Home Secretary under Mr Corbyn, said removing the whip “raises serious questions of due process”.

Len McCluskey, General Secretary of Unite – Labour’s biggest donor – said the refusal to restore the whip to Mr Corbyn was “vindictive and vengeful”.

He said on Twitter that the move “despoils Party democracy and due process alike and amounts to overruling the unanimous decision of the NEC panel yesterday to readmit him to the Party”.

Mr McCluskey added: “The continued persecution of Jeremy Corbyn, a politician who inspired millions, by a leadership capitulating to external pressure on Party procedures risks destroying the unity and integrity of the Party. I urge Keir Starmer in the strongest terms to pull back from the brink.”

Jon Lansman, founding member of Momentum, the Corbyn-supporting activist campaign, said the move not to restore the whip had “driven a coach and horses through the party’s disciplinary process, making it subservient to the parliamentary party and embedding “political interference”. Momentum has started a petition to secure Mr Corbyn’s reinstatement to the PLP.

However, Sir Keir’s action was welcomed by veteran Jewish Labour MP Dame Margaret Hodge, who said: “Yesterday has shown once again just how broken and unjust the existing complaints system is.

“It has caused untold hurt and anguish across the Jewish community, undermined progress made and made me question my own place in the party.

“As Corbyn has refused to himself accept the findings of the EHRC report, refused to apologise for his actions and refused to take any responsibility, withholding the whip is the right decision.”

Marie van der Zyl, President of the Board of Deputies of British Jews, said Labour’s disciplinary process was “clearly still not fit for purpose” but stressed Sir Keir had “taken the appropriate leadership decision not to restore the whip to Jeremy Corbyn”.

Sir Keir’s spokesman declined to get drawn into the party’s disciplinary process but insisted what people had in the Labour leader was someone who was “absolutely resolute in his determination to root out anti-Semitism and make the party a place for Jewish people once again”.

The issue of the whip being withheld from the former leader is now set to be discussed at the next meeting of the PLP on Monday. One senior figure said there might be a move by some MPs to seek Mr Corbyn’s reinstatement to the parliamentary party but they would not succeed. “The Left is very weak now; they have a social media presence but that’s it.”