"We led this search to find the truth, not to find the weapons. The fact that we found that so far the weapons did not exist, we've got to deal with that difference and understand why," Kay told National Public Radio.

Asked if he thought President George W. Bush owed the American public an explanation for the failure to find banned chemical or biological weapons, Kay said: "The intelligence community owes the president rather than the president owing the American people.

"We have to remember that this view of Iraq was held during (former president Bill) Clinton administration and didn't change in the Bush administration. It is not a political 'got you' issue. It is a serious issue of how you could come to the conclusion that is not matched by the future."

Kay stepped down Friday as leader of the Iraq Survey Group, which 10 months after the US and British invasion of Iraq has yet to find any of Saddam's feared weapons of mass destruction.

The failure to find banned weapons or programs has become a major embarrassment for Washington after it made them the central element of its case for war against Iraq.

He also expanded on remarks he made earlier to Britain's Sunday Telegraph newspaper, on the possibility that Saddam had sent some of his weapons to Syria before the war.

"There's ample evidence of movement to Syria before the war," he said. "There's satellite photography, there are reports on the ground, of a constant stream of trucks, cars, rail traffic across the border. We simply don't know what was moved."

"There's very little you can do in Iraq to determine what was moved. The real answers to that are in Syria, and the Syrian government has shown absolutely no interest in helping us resolve this issue," he said.

Kay's remarks also cast doubt on claims contained in a British government dossier which said in September 2002 that Iraq could deploy chemical or biological weapons in just 45 minutes.

"After the war and with the inspection effort that we have carried out now for nine months, I think we all agree that there were not large amounts of weapons available for imminent action," he said.

"That's not the same thing as saying it was not a serious, imminent threat that you're not willing to run for the nation. That is a political judgment, not a technical judgment."

US Secretary of State Colin Powell said Saturday it was "open question" as to whether Iraq still had such weapons, but he argued that pre-war intelligence was correct about Saddam's intention to develop them.

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