Ms Abbott, who has been a Labour MP since 1987, was yesterday suspended from the parliamentary party pending an investigation into her remarks, which were published in The Observer.

After being pressed three times, Mr Starmer said on Monday he believed her remarks were "antisemitic" and his party was "absolutely right" to act swiftly in response.

Ms Abbott has been criticised over a letter she wrote in the newspaper, which came in response to a separate article from Tomiwa Owolade which had the headline: "Racism in Britain is not black and white. It's far more complicated."

The Hackney North MP challenged Mr Owolade's claims that "Irish, Jewish and Traveller people all suffer from 'racism'", instead claiming that they "undoubtedly experience prejudice".

Ms Abbott said prejudice was "similar to racism and the two words are often used as if they are interchangeable".

Diane Abbott speaks out for first time since apology - politics latest

"It is true that many types of white people with points of difference, such as redheads, can experience this prejudice," she continued. "But they are not all their lives subject to racism."

The former shadow home secretary added: "In pre-civil rights America, Irish people, Jewish people and Travellers were not required to sit at the back of the bus.

"In apartheid South Africa, these groups were allowed to vote. And at the height of slavery, there were no white-seeming people manacled on the slave ships."

Ms Abbott, who now sits as an independent MP in the Commons, quickly apologised for her remarks.

Asked if what Ms Abbott wrote was antisemitic, Sir Keir told broadcasters: "What she wrote yesterday, I utterly condemn.

"And I said we would tear out antisemitism by its roots. I meant it, and that's why we acted so swiftly yesterday.

"I think it's a mark of how far the Labour Party has changed that we acted so swiftly and we take it so seriously. But I condemn what she said."

Pushed a second time on whether it was antisemitic, Sir Keir said: "I condemn what she said.

"There's an investigation going on now, but look, I don't think anybody can doubt the change in the Labour Party when you see such swift action and an absolute commitment to zero tolerance."

And at the third time of asking, the Labour leader said: "In my view, what she said was to be condemned, it was antisemitic. It's absolutely right that we acted as swiftly as we did."

Shortly after the letter was published, Ms Abbott issued a statement in which she said she wished to "wholly and unreservedly withdraw my remarks and disassociate myself from them".

"The errors arose in an initial draft being sent," she wrote.

"But there is no excuse, and I wish to apologise for any anguish caused."

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Has political trailblazer Diane Abbott trashed her own reputation?

The removal of the whip makes Ms Abbott the eighth MP to be suspended from Labour.

Rupa Huq, who had the whip suspended after being accused of making a racist comment about former chancellor Kwasi Kwarteng, has since been reinstated.

Jeremy Corbyn, who appointed Ms Abbott as shadow home secretary when he was leader, continues to sit as an independent MP after he was suspended by Labour over his reaction to a damning report by the Equality and Human Rights Commission into how antisemitism complaints were handled under his leadership.

Immediately after its publication, Mr Corbyn claimed "the scale of the problem" of Labour antisemitism allegations was "dramatically overstated for political reasons by our opponents".

Last month he was formally blocked from standing for Labour as a candidate at the next election.