The gloves finally came off in the Liberal Democrat leadership contest yesterday when Chris Huhne accused his rival, favourite Nick Clegg, of "flip-flopping" on policy.

The extraordinary attack came after it emerged that Mr Huhne's office had produced a document entitled "Calamity Clegg", which set out criticisms of the party's home affairs spokesman.

When Mr Huhne, LibDem environment spokesman, was presented with the document on television he claimed he had never seen it before. However, he went on to argue there were a series of issues, including Trident and school vouchers, on which "we don't know where Nick stands".

The 53-year-old Hampshire MP added: "I don't support describing anybody else in the party a calamity, that's absolute nonsense, but I do think we've had a series of flip-flops on this issue from Nick."

In a rowdy exchange, Mr Clegg, 40, who represents Sheffield Hallam, said he had repeated his positions until he was "blue in the face", adding he was "saddened" by his opponent's approach.

Turning to his opponent, he said: "This contest is not about me meeting false challenges that you put up to me. It's about me saying what I think the Liberal Democrats need to do for the country, to make Britain a more liberal place."

Ballot papers go out on Wednesday and the result will be announced on December 17.