In an outspoken interview with the Daily Mail, Mr Clarke says Justice Secretary Jack Straw is a "very hard person to work with" and criticises Home Secretary Jacqui Smith for admitting she was scared to walk about London at night.

He goes on to dismiss Mr Brown's Cabinet as "lightweight" and warns that the Prime Minister does not have the country's confidence.

Last month the former minister said Labour had "wasted much of the first half of this Parliament" in internal party squabbles and remained "very unclear" about what it had to offer voters in the next general election.

Mr Clarke, a close ally of Tony Blair when he was prime minister, was sacked as Home Secretary in May 2006 in the wake of the furore over 1,000 foreign prisoners released into the community without being considered for deportation.

Mr Clarke told the Mail: "The Prime Minister cannot bear anyone who challenges him. We are conveying a sense of drift and uncertainty. Only Gordon can change this - if he is capable of doing so. Unfortunately, he hasn't the confidence of the country because of the things he has done.

"I have to start a debate about all this because it is only two and a half years until the next general election, and it is imperative that there is a discussion of Labour's future before it has no future and is obliterated.

"There is a very big problem in Gordon's mind. He is always thinking about Tony Blair. It's a strange, tormented thing. He is tormented by the idea of Blair. It's almost a love-hate thing. He wants to be anti-Blair, rather than post-Blair. He wants to revisit things that Blair did, like casinos and cannabis."

He compares Mr Brown unfavourably to Conservative leader David Cameron, saying Mr Cameron acted quickly in response to the situation over MPs expenses, whereas Mr Brown "lacks courage" and "must stop being a ditherer".

Dismissing the current Cabinet as lightweight, Mr Clarke names "heavyweight" politicians he believes should join the Cabinet such as former Health Secretaries Alan Milburn and Patricia Hewitt, ex-Transport Secretary Stephen Byers and John Reid, who replaced Mr Clarke as Home Secretary.