Former Cabinet minister David Mellor has resigned from the Conservative Party.

He told the BBC that Iain Duncan Smith was a "sub-Blair creature" who was "devoid of any real personal distinction".

"I have actually ceased to be a member of the Conservative Party. It didn't seem worth renewing the membership. Until they rediscover a basic belief and a cutting edge I shall join the 54.5 million who are not members of a political party," he said.

But William Hague has renewed his backing for Duncan Smith.

Hague, who quit following his party's defeat in the 2001 general election, said on Sunday that his successor was "doing the right things".

He pointed to the party's strong showing in the local elections as proof that Duncan Smith had begun to make progress.

Speculation has been rife that he still hopes to return to frontbench politics - heightened by former Tory frontbencher Crispin Blunt's call for him to make a leadership bid - but the Richmond MP ruled out such a move in the short term.

"I no more sit there thinking that I want to be leader of the Conservative Party again than I think about being the next person to fly to the moon," he told the BBC.

"I have done that and I have had that experience. It didn't work out exactly as it was intended to, much as I enjoyed it. I am not looking to do it again or to come back into the front line of politics in any form in the next few years, so the answer is a categoric no."