A bitter row over the gossipy memoirs of top British politician Peter Mandelson is threatening to overshadow the Labour party’s election of a new leader to replace Gordon Brown.

Mr Mandelson was, with Mr Brown and Tony Blair, part of the most powerful troika in British politics until centre-left Labour was voted out of office and into opposition in May for the first time since 1997.

The flamboyant arch-spinner, nicknamed the "prince of darkness", was Mr Brown’s deputy Prime Minister and a controversial minister who quit twice under Mr Blair, giving him an unrivalled insight into the turbulent New Labour he helped to build.

Now the 56-year-old is telling all about his years as the power behind the throne in a memoir entitled The Third Man, out tomorrow, which has drawn a furious reaction from some Labour colleagues.

Early extracts published by The Times detail how Mr Brown’s hopes of clinging to power in May by forming a coalition with the centrist Liberal Democrats were scuppered by LibDem leader Nick Clegg, who said he could not work with him.

Mr Clegg now holds Mr Mandelson’s old job, serving as deputy to Conservative Prime Minister David Cameron in a coalition government which is imposing punishing spending cuts in a bid to reduce a record deficit accrued under Labour.

It is the timing of Mr Mandelson’s book which has caused anger – the memoirs have thrown the spotlight on Labour’s feud-ridden past, in the middle of a four-month-long leadership election.

Charlie Whelan, Mr Brown’s former spin doctor and one of his closest allies, accused Mr Mandelson, who ran the party’s failed re-election bid, of having concentrated on his book, not the election, in the run-up to May’s crunch poll.

"Peter ran the worst general campaign in Labour’s history. Nobody knew what the message was at all. It was a disaster from beginning to end," he told the Sunday Telegraph.

"Peter wasn’t focused on the campaign at all. Clearly his only thoughts were for his book."

Other Labour figures have been more scathing under cover of anonymity, with one saying that his decision to release the book now "beggars belief".

Even before the book row blew up, Labour’s leadership contenders – of whom the favourites are Mr Brown’s former foreign secretary David Miliband and his brother Ed – were struggling to focus on the future rather than shaking off past affiliations to Mr Blair or Mr Brown.

The two former premiers started out as close allies but fell out bitterly during Mr Blair’s premiership over his failure to hand over the job to Mr Brown as soon as Mr Brown wanted.

Ed Miliband – seen as a Brownite – has responded to the controversy by calling on everyone to start focusing on issues, not personalities.

"We do need to move on from some of the psychodramas of the past, some of the factionalism that there was," he told BBC radio. Mr Mandelson – who is promoting the book’s serialisation with a television advert where he sports a velvet smoking jacket and refers to the story of New Labour as like a fairytale – is not the only Labour big name to have signed a lucrative book deal.

Mr Blair is reportedly set to earn £4.6 million (€5.5 million) with his memoir, The Journey, out in September, although his aides deny he clashed with Mr Mandelson over the timing of publication.

Mr Brown is rarely seen in the House of Commons and is instead holed up at home in Scotland writing a book and even his wife Sarah has signed up with publishers.

Commentators argue the rash of memoirs will do no good. The Guardian’s Jackie Ashley wrote on Monday that they would likely "reopen the hideous wounds Labour inflicted on itself while in power.

"We saw it and heard it being reported at the time... at this most dangerous time for Labour’s future, yet more headline-grabbing rehashed descriptions of the ghastliness seem to me to be self-serving and undisciplined," she added.

Another Labour heavyweight, Mr Blair’s former deputy John Prescott, has suggested such feuds look petty as the Conservative-LibDem coalition prepares to impose spending cuts of around 25 per cent on most government departments.

"Can we put that behind us and can we concentrate on what people are concerned about in this country?" Mr Prescott told the BBC.