Allies of Gordon Brown have attacked the prime minister after he signalled his intention to remain in power for a third term.

The chancellor's associates have accused Tony Blair of turning his back on a succession deal.

Following his most turbulent period as prime minister, Blair insisted that his appetite for the role was "undiminished".

But he admitted that he has lost the trust of the British people following the war in Iraq.

Blair said the dispute over the dossier on Iraq's weapons of mass destruction and the failure to come up with proof of biological and chemical weapons in Iraq was a problem.

"There is an issue that we have to confront. People need to know that what we did in Iraq was right and justified," he said.

"That's a case we have to not just assert, but prove over time, both in relation to weapons of mass destruction and in relation to the improvement [of conditions in Iraq]."

The prime minister also avoided questions over his role in the death of the weapons expert David Kelly, saying that it was a matter for Lord Hutton's inquiry.