Mr Campbell's diaries were described to the committee as 'the Big C'

In a letter to the cross-party commons public administration committee he says his memoirs could be used to "damage" the government or the prime minister.

The former Downing Street director of communications said "for that reason alone" he had made the decision.

He plans a series of books about his time in politics "at some time".

'Detrimental'

Mr Campbell started working with Mr Blair after he became Labour leader in 1994 and became the prime minister's official spokesman after Labour's election victory in 1997.

He moved to the role of communications director in 2001, until he stepped down in August 2003.

His keenly-awaited memoirs had been widely expected for release as soon as Tony Blair stepped down.

But in his letter to the committee - which has been holding a high-profile inquiry into political memoirs - Mr Campbell wrote: "I would consider it wrong to publish in a manner or at a time detrimental to the interests of the government or the party I served."

'Damaged trust'

"With our media and politics as they are, I am in little doubt that publication would be used to try to damage the government, the Labour Party, the Prime Minister and others.

"For that reason alone I have decided against early publication."

Mr Campbell's diaries were thought to offer a unique insider's view of the rise of New Labour and of Tony Blair's time in power by his media chief.

But the action of Downing Street diarists, such as Mr Campbell came under fire from former senior No 10 official Geoff Mulgan, until 2004 a top aide to Tony Blair, who said diary-keeping by insiders damaged trust.

And the knowledge that ex-media chief Mr Campbell and others kept them probably "coloured" key discussions, he claimed.