London ? In an embarrassing about-face ahead of elections, Prime Minister Tony Blair on Thursday released a secret memo warning of the legal consequences of invading Iraq without a second U.N. resolution.

Blair had long refused to publish the March 7, 2003 document from Atty. Gen. Lord Goldsmith, saying it was confidential. Instead, the prime minister had consistently pointed to the written statement Goldsmith gave to parliament 10 days later, which said the war would be legal without another resolution.

Political opponents, who pressured Blair into releasing the text after it was leaked Wednesday night, said it showed the prime minister had deceived Britain.

Speaking to the House of Commons, Blair said last month that “if it is being said that the legal opinion of the attorney general was different from the attorney general’s statement to the House, that is patently absurd.”

The prime minister’s main electoral opponent, Conservative leader Michael Howard, said Thursday that “if you can’t trust Mr. Blair on the decision to take the country to war — the most important decision a prime minister can take — how can you trust Mr. Blair on anything else ever again?”

Blair insisted Goldsmith’s advice had been consistent.

“Whatever I say, I will never, ever convince some people who have been opposed to this war,” Blair said. “I cannot apologize for that decision because I still think the world is a better place with Saddam (Hussein) in prison rather than in power.”

Opinion polls show Blair’s Labor Party with a solid lead before the May 5 election but Blair’s about-face could derail the final days of his election campaign.

Goldsmith’s 13-page memo to Blair warns the government it would be safer to go to war with a second U.N. Security Council resolution specifically authorizing military action. It also warned that British troops taking part in the conflict could be open to legal action.

Prime Minister Tony Blair, trying to defuse a row over Iraq a week before Britain's general election, has released the attorney general's advice on the legality of the U.S.-led war -- something he had long refused to do. Thursday's announcement came after a TV channel said it had obtained a leaked copy of a memo sent to Blair from Atty. Gen. Lord Goldsmith in which he warned the invasion could be deemed illegal without a second U.N. Security Council resolution authorizing military action.

Ten days later, Goldsmith said the war would be legal without a further resolution. Opponents insist there is a clear difference between Goldsmith’s views in the March 7 and March 17 documents, and question whether the attorney general was leaned on politically.

Howard, who has branded Blair a liar, said the document reinforced doubts about Blair’s integrity and ability to lead the country.

Blair had refused to publish the memo, arguing as late as Wednesday night that it would set a dangerous precedent to release confidential legal advice.

But on Thursday he said: “You have probably got it all anyway. I see no reason not to publish it.

“The key thing was the attorney general advising it was lawful to proceed. This so-called smoking gun has turned out to be a damp squib, because he did advise it was lawful to proceed,” Blair said.