In an interview with chat show host Michael Parkinson to be broadcast on Britain's ITV1 television on Saturday, Blair said he made policy decisions according to his conscience, which is guided by his Christian faith.
Asked about joining the US-led invasion in March 2003, he said: "That decision has to be taken and has to be lived with, and in the end there is a judgment that - well, I think if you have faith about these things then you realise that judgment is made by other people." Pushed to clarify what he meant, Blair, a devout Christian, replied: "If you believe in God, it's made by God as well."
He said: "This is not just a matter of a policy here or a thing there, but of their lives and in some case their death... the only way you can take a decision like that is to try to do the right thing, according to your conscience and for the rest of it you leave it to the judgment that history will make."
Parkinson asked Blair whether he prays to God when making a decision such as going to war.
He responded: "Well, I don't want to get into something like that."
Pressed on the subject Blair answered: "Of course you struggle with your own conscience about it because people's lives are affected and it's one of these situations that I suppose very few people ever find themselves in. In the end you do what you think is the right thing."
In October last year US president George W. Bush US allegedly said God told him to invade Iraq and Afghanistan, according to a report.
Blair's comments were immediately criticised by opposition political parties and families of some of the 103 British soldiers who have died since the start of the conflict.
Menzies Campbell, leader of the smaller opposition Liberal Democrats, which opposed military action, said: "Going to war isn't just an act of faith, it requires rigorous analysis of the legality of doing so, the likelihood of success, the number of possible casualties and the long-term consequences.
"My complaint of the prime minister is that while he may have believed what he was doing was right, the prospectus for military action was flawed."
Reg Keys, whose son Tom was one of six Royal Military Police officers killed by an Iraqi mob in June 2003, said God and religion had nothing to do with the conflict.
"This is his (Blair's) effort to fudge it. War should be the final option that a prime minister takes when all avenues have failed," said Keys, who stood against the prime minister in the last general election on an anti-war ticket.
News24Last Mod: 20 Eylül 2018, 18:16