US justification for the war has come under a new spotlight since David Kay stood down as the head of the Iraq Survey Group last week and said weapons of mass destruction would probably never be found.

But Kay said Tuesday that the war had been "absolutely prudent" to stop terrorists from getting their hands on such arms.

And Bush followed this up by reaffirming his faith in the US intelligence used to justify the invasion to oust the Iraqi president.

"There is no doubt in my mind the world is a better place without Saddam Hussein. America is more secure, the world is safer, and the people of Iraq are free," Bush said in a meeting with Poland's President Aleksander Kwasniewski.

Bush said the Iraq Survey Group would continue to "gather the facts" in Iraq and added: "There is no doubt in my mind that Saddam Hussein was a grave and gathering threat to America and the world.

"There's just no doubt in my mind. And I say that based upon intelligence that I saw prior to the decision to go into Iraq and I say that based upon what I know today," the US president said.

"The world is better off without him."

Bush said he had "great confidence" in US intelligence and that information about Iraq's weapons had come "from years of intelligence, not only our own intelligence services, but other intelligence-gathering organizations."

The case for war has been at the centre of an intense international debate, with several countries lined up against the United States and its allies at the United Nations.

The administration has gone back on the offensive after Secretary of State Colin Powell said Saturday that it was an open question whether Saddam had chemical, biological or nuclear weapons at the time of the invasion last March. Kay said Sunday he did not think Saddam possessed such arms.

But the expert said Tuesday: "I think at the end of the inspection process, we'll paint a picture of Iraq that was far more dangerous than even we thought it was before the war.

"It was of a system collapsing. It was a country that had the capability in weapons of mass destruction areas, and ... terrorists, like ants to honey, were going after it."

Kay told NBC television that before the war, Britain, France, Germany and the United Nations "all thought Saddam had weapons of mass destruction. Not discovering them tells us we've got a more fundamental problem."

He said "the tendency to say, well, it must have been pressure from the White House, is absolutely wrong."

Saddam "was putting more money into his nuclear program, he was pushing ahead his long-range missile program as hard as he could."

"We have collected dozens of examples of where he lied to the UN, violated Resolution 1441 and was in material breach," Kay added.

He noted that Saddam "had the intent to acquire these weapons. He invested huge amounts of money in them. The fact is, he wasn't successful."

In addition, he said it was "quite common" for Iraqi scientists to be "reporting back successes that they were not having." There was "a tremendous amount of corruption there and lying that went on there" in Iraq.

He said the scientists described to him an Iraq, from 1998 on, "that was descending into the utter inability to do anything organized. Corruption was there. They couldn't get the equipment. Money was wasted."

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