London Mayor Boris Johnson has said he does not expect to do "another big job in politics" after leaving City Hall.

Mr Johnson, tipped as a possible successor to Tory leader David Cameron, ruled out standing as an MP while also mayor - meaning he would be unable to seize the Conservative leadership.

Current rules say the leader must be an MP - and he quashed as "complete nonsense" suggestions he could perform a dual role if he is re-elected as mayor in May 2012.

He told ITV London Tonight: "Let's take this opportunity to knock this on the head.

"The job of Mayor of London is the most wonderful, most engrossing, job I could ever imagine I would have in politics and loads of people realise how lucky I am to be here... and I really don't want to do anything else. What I want is to get re-elected.

"I've said that I won't go beyond a second term. I'll be well-struck in years."

In an interview for BBC2's Newsnight, Mr Johnson said there is "not a snowball's chance in Hades" he would stand for Parliament while mayor, adding: "I don't think I will do another big job in politics after this."