PM's vow on Labour election victory

While claiming again that he had no interest in the trappings of power for their own sake, he insisted he still had a mission to accomplish as Prime Minister.

"It is because of my purpose in politics that I am determined to lead Labour to the next general election. We must and we will win," he told the News of the World.

His comments come in the aftermath of a failed backbench bid to oust him and a string of resignations from his Government as Labour crashed to its lowest election results since the First World War.

Polling in recent months has seen Labour struggling to reduce a Tory lead sometimes in excess of 20 points.

He suggested in the immediate aftermath of the attempted coup earlier this month that he could happily walk out of Downing Street at any time.

But he has now dispelled any doubts that he will fight on until the next election, in a warning to plotters who are expected to mount another attempt to lever him out at this autumn's Labour conference.

With the parliamentary expenses row continuing to rage, Mr Brown warned MPs they should spend the summer engaging with their constituents.

"It has never been the trapping of power I care about but what we can do in power to help hard-pressed families," he said. "I believe that it is the responsibility of Members of Parliament to serve the constituent and one way they can is by rebuilding whatever trust was lost."

Mr Brown's remarks came after The Guardian published an interview in which he spoke of his "hurt" at some of the criticism levelled at him and admitted recent events have been among the worst of his political career.