Tony Blair has revealed he disregarded his top legal adviser's warning that attacking Iraq would be illegal without further UN backing because the guidance was "provisional".
The former Prime Minister made the revelation in a statement ahead of his second appearance at the Chilcot Inquiry into the March 2003 invasion.
He was questioned by inquiry chairman Sir John Chilcot and his panel about possible gaps and inconsistencies in Mr Blair's justification for the war.
The-then Attorney General Lord Goldsmith told him on January 14 2003 that UN Resolution 1441 was not enough on its own to justify the use of force against Saddam Hussein.
But the next day Mr Blair told the Commons it was necessary to be able to say that Britain would still act if an unreasonable veto at the UN was put down.
Mr Blair has now said: "I had not yet got to the stage of a formal request for advice and neither had he got to the point of formally giving it.
"So I was continuing to hold to the position that another resolution was not necessary."
The peer revealed he was "uncomfortable" about Mr Blair's public comments that Britain could attack Iraq without further UN support.
Mr Blair said he believed Lord Goldsmith would come around to his interpretation of the legal position once he knew the full history of the negotiations behind Resolution 1441.
And in March 2003 before the invasion, Lord Goldsmith presented him with formal legal advice that a "reasonable case" could be made for launching an attack without extra UN backing.
Meanwhile, Mr Blair privately assured US President George Bush "you can count on us" in the run-up to the war.
The view was in a private note that will remain secret but Mr Blair summed up its contents and that of other statements to Mr Bush.
He said he had told Mr Bush: "You can count on us, we are going to be with you in tackling this, but here are the difficulties."
The inquiry released a newly declassified document from March 2002 in which Mr Blair said the UK should be "gung ho" about the prospect of getting rid of the Iraqi dictator.
In his evidence to the inquiry, Mr Blair said he made clear that he would always stand "shoulder to shoulder" with the Americans.
But he also claimed he succeeded in persuading the US leader to go down the "UN route" first.
The former Premier said regime change in Baghdad had always been "on the agenda" for the Americans after the 9/11 attacks in 2001.
He said the US/UK were trying to get a second UN resolution, and Chile and Mexico wanted to support them but France was threatening a veto.
He claimed the French were clear they would veto any resolution that included an ultimatum, and the US/French relationship had become "very scratchy".
Mr Blair said France believed Saddam was complying in part with weapons inspectors. The US was arguing he was not fully complying. Mr Blair claimed without full compliance, action must follow.
The ex-PM argued that if US/UK had backed off from Iraq in March 2003, it was at least possible that Saddam would still be there now with WMD.