The latest revelations emerged after the Prime Minister was forced to deny knowing anything about Alistair Darling's extraordinary claim that the 'forces of hell' were unleashed on him by No 10.
He claimed there was a 'family' atmosphere inside Downing Street as the Tories said it was clear the two men at the top of the Government were at war.
Mr Darling's declaration fuelled speculation that he is again at odds with Mr Brown over the pre-election Budget.
The Chancellor is determined to flesh out details of a 'credible' medium-term plan to rein in the spiralling budget deficit and calm jittery financial markets, while the Prime Minister wants to focus on protecting spending on frontline public services, according to Government sources.
MPs saw Mr Darling's claim that Downing Street had subjected him to vicious anonymous criticism as an assertion of independence ahead of the Budget.