George W. Bush and Tony Blair probably knew they were exaggerating the threat from Iraq when they were making the case for war, according to former chief UN weapons inspector Hans Blix.
The US president and the British prime minister ignored the few caveats in reports from intelligence services on Iraq's nuclear, chemical or biological weapons programmes, he writes in his account of the months leading up to the US-led invasion.
Blix says it was "probable that the governments were conscious that they were exaggerating the risks they saw in order to get the political support they would not otherwise have had".
In an interview from Stockholm, Blix highlighted the now discredited British claim that Iraq had weapons of mass destruction that could be deployed within 45 minutes.
"They must have had a half-conscious idea that this was perhaps a bit of exaggeration...The aim of it I think was to create an impression in the reader that they were faced with something very ominous," he said by telephone.
"If they had been more critical of the evidence they saw, I think that they should have put some question marks rather than the exclamation marks that they did," he added.
Blix was head of the International Atomic Energy Agency from 1981 to 1997 and later chief of UNMOVIC (the UN Monitoring, Verification and Inspection Commission) until 2003.
At other points in his book "Disarming Iraq - The search for weapons of mass destruction", due to go on sale on Tuesday, the former Swedish diplomat appears to soften his criticism of the British and American leaders.
"I am not suggesting that Blair and Bush spoke in bad faith, but I am suggesting that it would not have taken much critical thinking on their own part or the part of their close advisers to prevent statements that misled the public," he writes.
"It is understood and accepted that governments must simplify complex international matters in explaining them to the public in democratic states.
Blix says he too had believed Iraqi President Saddam Hussein had illegal weapons. But he adds he was unwilling to state it as fact until he saw concrete proof - which was never obtained by his teams of inspectors scouring the Iraqi countryside.
Blix told Reuters he believed Bush and Blair had damaged both their own credibility and that of the United Nations, but that he expected all to recover in due time.