Downing Street has denied that the prime minister's relaxed approach to running the country has resulted in the chancellor out-manoeuvring him on the single currency.

Insisting that Tony Blair had a strong work ethic, Number 10 defended his official routine following an intervention by Peter Mandelson.

At a lunchtime briefing on Tuesday the former Northern Ireland secretary said the prime minister did not share the chancellor's obsessive working patterns.

Mandelson claimed the chancellor was "a politician right down to his fingertips, 24 hours a day, seven days a week".

That quality had allowed Gordon Brown to pull one over on his boss, said the Hartlepool MP who was twice sacked by Blair.

"If he [Blair] was as obsessed with politics, he would not have let himself be outmanoeuvred by the chancellor in the way that he potentially has," Mandelson told journalists.

A spokesman for the prime minister - who is said to play his guitar at his Chequers retreat to escape the stress of high office - dismissed Mandelson's account of events.

"The prime minister works very hard...We all need to eat [and] sleep," said his official spokesman.