Lord Kinnock said Mr Miliband will not stand

Lord Kinnock told Channel 4 News he was in "despair" at his close friend and former chief of staff's actions.

Mr Clarke has repeatedly urged David Miliband to stand - and has not ruled out a bid for the top job himself.

Mr Miliband appeared to rule himself out of the race on Tuesday telling the BBC he was "not a candidate".

Mr Brown is the favourite to take over when Tony Blair stands down as Labour leader, which he is expected to do shortly after 3 May's elections in Scotland, Wales and English local councils.

Lord Kinnock said continued speculation about a Cabinet-level challenge to Gordon Brown - fuelled by Mr Clarke - was a "distraction" and was "doing no good" to the party.

'Comrade'

He said it was "unreal" to think that Mr Clarke stood any chance of winning a significant number of votes in a contest with Mr Brown.

And he said he was "absolutely, definitely, beyond peradventure, 22-carat certain that David [Miliband] never was going to run and certainly isn't going to run".

Lord Kinnock said he did not know whether Mr Clarke would stand as a Blairite candidate against Mr Brown.

He told Channel 4 News: "I am in despair, to a certain extent, not only because of the distraction but also because this is my very, very dear friend and comrade who I think has somehow got himself into a situation where he is saying things that do him no good - and I bemoan that greatly - and in the end do the Labour Party not much good.

"When he analyses it, that will distress him as much as it does me, because Charles is someone who so fundamentally wants the Labour Party to succeed and advance."

'Not wavering'

He added: "It isn't reality that if Charles was to run he could secure a significant vote. I don't know even if he could get the 44 signatures required - he may, he may not.

"What I do think is that, for some reason that I am not familiar with - and I have talked to Charles, he is my very, very cherished friend - for some reason or other, he has decided to take this course.

"I don't think it is constructive. I don't think it benefits him and I am concerned about that, and I know that it is not of assistance to the Labour Party."

Lord Kinnock said Mr Miliband was right not to rule out ever standing for the Labour leadership, as he would be a good candidate in future elections after serving in ministerial office under Mr Brown.

Mr Miliband was asked on Tuesday in a BBC interview whether he would run for the Labour whether he would run for the Labour leadership.

He said: "Well I've not wavered in my view over the last three years and I'm not wavering now.

"I've meant what I said, I am not a candidate, we've got an excellent prime minister in waiting in Gordon Brown, and I'm getting on with my job as environment secretary which I think is one of the most pressing issues that we face."