Tony Blair's main rival accused him of lying over the Iraq war, seeking to damage the prime minister over an issue that could prove the weakest link in his campaign for re-election on May 5. Polls put the centre-left Labour party on course for an unprecedented third term but point to the first real electoral contest since 1992. The impact of Iraq remains a big unknown.

Conservative leader Michael Howard, who backed the conflict, urged voters to pass judgement on Blair's integrity while the third-placed Liberal Democrats prepared to put Iraq at the heart of their campaign to capitalise on their opposition to the war.

"He has told lies to win elections. On the one thing on which he has taken a stand in the eight years he has been prime minister, which is taking us to war, he didn't even tell the truth on that," Howard said.

The charge - Howard's most vicious attack yet on Blair's honesty - overshadowed the prime minister's efforts to flag up his commitment to international aid on World Poverty Day.

With polls showing the Conservatives have failed to make inroads on voters' main priorities like health and education, Howard sought to turn the poll into a referendum on Blair.

The election was the public's last chance to "make a judgement on Blair's character," Howard said, adding the prime minister had made many "broken promises" including on tax.

With 11 days left until the British general elections, a pair of fresh opinion polls showed Blair's Labour Party still in the lead, and voters largely bored.

A YouGov poll in the Sunday Times put Labour at 37 per cent, compared with 33pc for the main opposition Conservatives led by Michael Howard and 23pc for the Liberal Democrats led by Charles Kennedy.

l Former US president Bill Clinton endorsed Blair's campaign to be elected for a third straight term.

"We just need leadership, and Tony Blair, Gordon Brown and new Labour are providing that leadership," Clinton told the London audience.

PHOTO CAPTION