Brown leadership 'still threatened'

He said a "small group" within the party would never be reconciled to Mr Brown's leadership, but insisted he would not "lose any sleep" over it.

Meanwhile, Foreign Secretary David Miliband indicated that he had considered following James Purnell in quitting the Cabinet last Thursday.

Mr Miliband told The Guardian that he accepted his old friend's decision to resign as Work and Pensions Secretary was made "in good faith".

Their comments came as former Home Secretary Charles Clarke said that Mr Brown must win two upcoming by-elections in Norwich North and Glasgow North-East and improve Labour's standing in the polls if he was to escape calls for his removal.

Mr Clarke is expected to use a BBC interview on Sunday to indicate that he still wants Mr Brown to go.

And prominent backbencher Jon Cruddas warned that Labour could be finished as a major force in British politics unless it had a fundamental rethink of its policies and approach.

In an interview with the Daily Telegraph, Lord Mandelson acknowledged that Mr Brown had not silenced his internal party critics when he faced down demands for his resignation at a meeting of the Parliamentary Labour Party in Westminster on Monday.

"There's a small group who keep coming back. They won't be reconciled to the Prime Minister's leadership," said Lord Mandelson, who was last week named First Secretary of State - effectively deputy prime minister.

Mr Miliband left no doubt that he was faced with a decision over whether to stand down as Foreign Secretary last week during a reshuffle which saw 10 ministers leave the Government. Many commentators believe that if he had followed Mr Purnell in quitting as polls in the council and European elections closed on Thursday night, he would have forced Mr Brown out of office.