Diane Abbott: I told ex-Labour leader Jeremy Corbyn not to launch his new party

Ms Abbott, the independent MP for Hackney North and Stoke Newington, said she understood why her close ally had made the move. But she insisted it was "difficult to see how a new party wins" under the first-past-the-post electoral system.

Mr Corbyn launched the new venture last month with former Labour MP Zarah Sultana. It does not yet have a name, but is marketed as “Your Party”. He has vowed it will “take on the rich and powerful”.

Ms Abbot, who was the shadow home secretary under Mr Corbyn, was asked about the move while appearing at the Edinburgh International Book Festival on Thursday to discuss her memoir, A Woman Like Me.

She said there was a "tricky state of play", adding: "I wouldn't have thought that you would have a Labour government and they'd be cutting winter fuel allowance for the elderly, they'd be cutting benefits for the disabled."

However, she added: "I told him [Mr Corbyn] not to. It's very difficult under the first-past-the-post system for a new party to absolutely win.

"If it wasn't first past the post, then you could see how a new party could come through. But I understand why he did it.

"I understand why Zarah did it. Zarah is a lovely person, full of energy, and I think she and Jeremy are a great combination. But at this point in time, it's difficult to see how a brand new party wins.

"However, I think Jeremy's party is going to do a lot better than people think, because a lot of people - not necessarily terribly left-wing people - are a tiny bit disappointed about the way we've gone in the party."

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Last month, Ms Abbott was suspended from Labour for a second time, after she doubled down on comments about racism for which she had previously apologised.

She defended a letter she had written to a newspaper in 2023 in which she compared the racism experienced by people of colour with that seen by other groups.

Former shadow chancellor John McDonnell, another key ally of Mr Corbyn, has also ruled out joining his new party. "Just to be absolutely clear, I am a Labour Party member,” he said last month. “I have had the whip suspended, that's all, and I expect it back."

Earlier this month, Chancellor Rachel Reeves said the public would reject Mr Corbyn’s party like they rejected him twice before.

She told an audience at the Edinburgh Fringe Festival that Mr Corbyn had “tried to destroy my party” during his leadership in which he lost two general elections, one in 2017 and one in 2019.

“The country has rejected him twice," Ms Reeves said. "The bloke’s got a big ego. He can have another go, but I think the country will have the same verdict.”

Ms Abbott also told the book festival event the decision to ban Palestine Action as a terrorist group was a “disgrace” and “absolutely dreadful”.

She was elected to Parliament in 1987, and was the only black female MP in the Commons for a decade until Labour’s landslide under Tony Blair.

In response to a question about whether she thought she would ever be accepted “at the heart” of the Labour Party, she replied: “I think I am at the heart of the Labour Party, it’s other people who aren’t.”