Former Chancellor Alistair Darling will lift the lid on Gordon Brown's increasingly "brutal and volcanic" demeanour when his memoirs are published next week, according to a Labour-supporting blog.
Back from the Brink: 1,000 days at No 11 is said to reveal the true scale of behind the scenes feuding that dominated the Government during the financial crash.
Labour Uncut claims to have seen extracts of the book, due out next Wednesday, detailing a total breakdown in trust between the Prime Minister and Chancellor.
Mr Darling is reported to single out shadow chancellor Ed Balls and former business minister Shriti Vadera who, as key allies of the former Prime Minister, were running what amounted to a parallel Treasury operation within Government.
The blog also claims the book confirms the rumours that the former Prime Minister tried to sack the Chancellor in 2009.
Offered a more junior Cabinet role, Mr Darling threatened to walk out of government. Mr Brown, severely weakened by the economic crisis and plummeting poll ratings, relented and let him remain at No 11.
Atlantic Books, which is publishing the diaries, refused to comment on the story.
A Sunday newspaper has been signed up to serialise extracts this weekend.
Conservative party chairman Sayeeda Warsi seized on the claims as proof that key Labour figures put party infighting above the nation's interests.
She said: "Alistair Darling's memoirs should give Ed Miliband some concerns about Ed Balls' suitability to be shadow chancellor.
"Ed Balls recently claimed that he 'did his politics on the record', but he has already been shown to have been at the heart of the plot to oust Tony Blair. Now Alistair Darling accuses him of running a shadow Treasury operation within his own government. No wonder Labour left the nation's finances in such a mess when they put party political plotting above the national interest."