Britain's Labour Party, ousted from power after 13 years of rule, risks seeing divisions reopened by the publication of the memoirs of former minister Peter Mandelson, long at the heart of its internal intrigues.

Mandelson, who worked with former prime ministers Tony Blair and Gordon Brown, lays bare the tensions between the two men, telling the Times in an interview that Blair had to devote too much energy to dealing "with this insurgency from next door."

While the divisions between Blair, prime minister from 1997-2007, and his former finance minister and successor Brown have been well documented, Mandelson's account comes when Labour is adapting to life in opposition and effectively rudderless.

The centre-left party is conducting a drawn-out leadership fight after Brown stepped down in May following electoral defeat. Among the main candidates are former foreign secretary David Miliband, seen as the "heir to Blair" and as likely to steer a centrist course; former schools secretary Ed Balls, who was a close aide to Brown and is close to the unions who help to bankroll the party; and Ed Miliband, younger brother of David, a consensual figure who has good relations with both camps.

The new leader will not be named until the party's annual conference on Sept. 25, leaving a vacuum which Mandelson's "The Third Man" memoir and a book by Blair due at the start of September will help to fill.

Media stories suggested that Blair was angry that his former lieutenant beat him to the punch by publishing his memoirs just two months after the election defeat.

Book Wars
The book is published by Harper Collins on Thursday and serialisation began in British newspaper The Times on Monday.

Mandelson, a master of political spin, twice had to resign from ministerial roles under Blair. Brown brought him back into government in 2008 after he served as a European Commissioner and he became the most influential minister in the cabinet.

Mandelson has so far refused to endorse any of the candidates in the five-person leadership battle which is completed by former health secretary Andy Burnham and backbench MP Diane Abbott.

The fresh-faced Burnham has turned his fire on Mandelson, one of the architects of the New Labour project that brought Blair to power after 18 years of Conservative rule.

"There was far too much self-indulgent and egotistical factionalism and people spending their weekends at London dinner parties plotting the demise of other people in the Labour Party," Burnham told the BBC.

"We need a complete break from all of that - we don't need more of the same and I can bring the change that Labour needs in this next period," he said.

Years of Infighting
Some indication of Mandelson’s thoughts came over the weekend, when in an interview published in The Times, he said he regretted the years of infighting which hampered the government.

Brown and Mandelson fell out when Mandelson supported Blair’s successful party leadership bid in 1994. The rift was healed only after Brown became prime minister. He said in the interview that Brown had frequently asked him, “Why are we doing this to each other?”

Mandelson added that some of Brown’s aides were critical of Blair, and they tended to feed Brown’s resentment.