Britain's Tony Blair will face a fresh barrage of criticism this week over his decision to attack Iraq after a stinging by-election defeat raised the threat of a voter backlash in a general election likely within a year. The prime minister will defend his Iraq policy at a parliamentary debate tomorrow, with opponents accusing him of misleading Britain over Iraq's alleged weapons of mass destruction - the reason given for a war most Britons opposed. Blair remains on track to win a third term in an election he is expected to call in the first half of next year but Iraq has crushed his public trust ratings and voter anger over the war could slash his Labour Party's massive parliamentary majority. "What's absolutely clear now is that in order to try and win round the Labour rebels, Tony Blair actually deceived his own party and thereby deceived parliament and deceived the public," said Tim Yeo, MP for the opposition Conservative Party. Asked on Sky News if Blair had "knowingly" misled MPs over Iraq's weapons, Yeo said: "I believe so." Iraq hit Blair in parliamentary by-elections on Thursday. The anti-war Liberal Democrats, Britain's third party, overturned a Labour majority of more than 13,000 to win one seat and almost won a second Labour stronghold. The polls - which reflected Labour's poor performance in June local council and European elections - came one day after a report exposed gaping holes in the pre-war intelligence on Iraq's lethal weapons. The report, by Lord Butler, absolved Blair of distorting intelligence but it contradicted claims Iraq's banned weapons were ready for use and showed that vital caveats were dropped from the spies' assessments. Former United Nations weapons inspector Hans Blix told ITV Television Blair had built the case for war on an "erroneous diagnosis". "The effect of it was to mislead but I don't think it was done deliberately ... There was an error of judgment," he said. Blair, who marks 10 years as Labour leader on Wednesday, now wants to shift the focus to domestic issues. He will launch his government's five-year strategy on tackling crime today. But it remains to be seen if Blair can regain voters' trust. A YouGov poll for The Sunday Times showed that 57 per cent of voters would not trust Blair to take Britain to war again, but also showed the Conservatives, who came an embarrassing third in by-elections, are far from power. "The shine has gone off him (Blair). But on current form, Labour will still win the next election comfortably," YouGov pollster Peter Kellner said. If is only because people do not see the Conservatives as a viable alternative. "It is surprising (US President George W Bush and Blair) are not even doing worse. The chief reason is that the only opponents with a hope of replacing them remain caught on the hook of their original support for the war," the Financial Times said. Conservative leader Michael Howard told the Sunday Times that he would not have backed the war decision had he known that the intelligence was so flawed **PHOTO CAPTION*** A protester wearing a mask depicting Britain's Prime Minister Tony Blair carries a model missile past a police officer as part of a demonstration by the group Campaign Against Arms Trade outside the Farnborough International Air Show, in Hampshire, southern England, July 19, 2004. (REUTERS)