Nick Clegg has said the Liberal Democrats would only join a coalition government in a hung parliament in exchange for a "complete reinvention" of British politics.

He told BBC Radio 4's Today programme he would not allow the party to become an "annexe" of a Labour or a Conservative government.

He said: "Any government that the Liberal Democrats would be part of would be on the back of a complete reinvention of the way we do politics to make it more accountable; to take the big money out of it; to make it more transparent; and above all to make it more decentralised.

"The week of the local elections is a good time to remind ourselves that we should be giving families and local communities more power over the way they run their own things."

He said he was "extremely pleased" at the party's performance in the polls.

"The polls yesterday were 20 per cent - that's considerably better than the 13 per cent of two or three years ago and far, far higher than we have ever been at this point in the political cycle, two or three years after a general election."

Clegg denied the suggestion that he was being overshadowed by Treasury spokesman Vince Cable, who served as acting leader after the resignation of Sir Menzies Campbell.

He said: "I don't think Vince and I think about it in those terms at all.

"Vince and I talk regularly, we recognise that we have different skills, different weaknesses, different strengths."

He added that Cable was "far outstripping" shadow chancellor George Osborne.