In a question and answer session with BBC News Online users after the publication of the London Bill setting out plans for a mayor, the Brent East MP said he did not blame the prime minister for junior Labour officials "all running around trying to please the leader".

Asked if he believed Mr Blair regarded him as too much of a threat to his own leadership, Mr Livingstone said he thought Mr Blair was reserving judgement.

"At the moment I genuinely think that Tony Blair has yet to make up his mind on this subject," he said.

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"The problem is that lower down the food chain, the Millbank Tendency are all running around trying to please the leader, assuming that they know what the leader wants.

"In my view, Alastair Campbell's briefing to the press that Tony Blair had not 'blackballed' me is probably correct."

Mr Livingstone added that the Labour Party could not simply ignore his own popularity, which has been reflected in a number of opinion polls putting him ahead in the race for London mayor.

"I also think that Tony Blair is keen on winning elections, which means that he has to weigh the competing demands for 'discipline' and control with the need to present the Labour Party in the best possible light.

The Millbank Tendency is behind the "blackball" campaign, Livingstone insists

"Since I am currently the front runner, I would not exclude the possibility that Tony can be persuaded on this issue!"

Other questions ranged over a wide variety of subjects. One user wrote that he had met Mr Livingstone at a party and had been impressed by his dancefloor skills.

"Do you believe your prowess at dancing and carousing will help you in your new endeavour of becoming Mayor of London?" asked Robert Myles.

In response, Mr Livingstone gave a pre-election commitment, which may yet come back to haunt him.

"Anyone who has seen me dance will know how bizarre your question is!