The former Prime Minister, now Middle East envoy for the Quartet group of the US, UN, EU and Russia, does not know whether history will vindicate him over the decision to invade. “I don't know. Nobody knows,” he told Ginny Dougary in an interview to be published tomorrow.
He said that he was not haunted by it “but of course I reflect on it, and am troubled by it, and feel a great sense of responsibility for it”.
He also delivered his frankest remarks about his wife, Cherie, and his property portfolio.
Iraq was the defining issue of Mr Blair's premiership, one that brought about his slide from being one of Britain's most popular leaders to one of its least popular.
Mr Blair said that it was not nice to have people distrusting his motives or saying that he had lied “but the most difficult thing in any set of circumstances is the sense of responsibility for people who have given their lives and fallen - the soldiers and the civilians. If I did not feel that, there really would be something wrong with me, and there is not a single day of my life when I do not reflect upon it . . . many times. And that's as it should be.”
He added: “On the other hand you have to take the decision and I look at the Middle East now and I think, well, if Saddam and his two sons were still running Iraq how many other people would have died and would the region be more stable?”
He admitted that he suffered from doubt over Iraq. “Of course you ask that question the whole time. You'd be weird if you didn't ask that question.”
In the wideranging interview with The Times Magazine, in which he has given his detailed thoughts on the Middle East peace process, Mr Blair compared President Obama to himself as a leader who is more interested in the practical than the ideological.
When it was put to Mr Blair that the euphoric mood in the US on Inauguration Day was similar to that in Britain after he was elected in 1997, Mr Blair agreed. “I think there is a new generation of political leaders who find the very traditional pigeonholing rather redundant, actually,” he said.
“They have undergone this strange experience, certainly for me, but in a sense I think for Obama too, which is growing up with a Left politics that was the politics of ideology, and then as we've grown to political maturity and taken positions of power, we find that it's the Right that's got ideology. Over time the centre Left became quite practical and the Right suddenly got ideology which I think still dogs it.”
Mr Blair has met Mr Obama several times since their first encounter when he was on the Senate Foreign Relations Committee. “He was introduced to me then as someone who was very clever and a great prospect for the future.” He was moved deeply by Mr Obama's speech on race. “That was when I understood that he had real political depth and imagination because it was not an ordinary speech. It showed a complete understanding of why people might feel as they feel but that actually it is time to move on. The thing he does brilliantly is to explain why certain sentiments are inconsistent with the future and can be put to one side.
“Prejudice certainly, but also that he understands that very partisan politics doesn't really work any more and doesn't meet either the needs of the time or the mood of the time.”
Mr Blair has revealed that he has more people working for him - 70 - than when he was in No 10. They are working for his sports foundation in the North East, his faith foundation, on his two governance projects in Sierra Leone and Rwanda, in his London office and as part of his Middle East team.
The former Prime Minister, whose earnings have soared into the millions since he left Parliament, said that he did not feel guilty about having houses in London and the country, as well as his home in his former constituency of Sedgefield, now the base of the sports foundation. His place in the country was a “nice house but not a stately home”.