Powell made public his doubts virtually a year to the day after he made the US case for war in a crucial speech to the UN Security Council. But he insisted that the United States was still right to launch the invasion last March.

The secretary of state said that even without weapons of mass destruction, Iraq's President Saddam Hussein still wanted them. He told the Post the administration's claims that Saddam already had chemical, biological and nuclear arms had just made the case for war more urgent.

Asked if he would have recommended an invasion if he had known Iraq had no banned weapons, Powell replied: "I don't know, because it was the stockpile that presented the final little piece that made it more of a real and present danger and threat to the region and to the world."

He said the "absence of a stockpile changes the political calculus; it changes the answer you get."

The Washington Post said that throughout the interview on Monday, the secretary of state "tried to balance the administration's rationale for going to war with the reality that no weapons of mass destruction have been uncovered in Iraq."

President George W. Bush on Monday ordered an independent investigation into the intelligence failure over Iraq's arms. The administration has faced mounting pressure over Iraq since former chief US weapons inspector David Kay said last week that no banned weapons would be found in Iraq.

Powell insisted, however, that ultimately the war will be judged as having been "the right thing to do."

Powell went before the UN Security Council on February 5 last year to make the US case that the world had to act over Saddam's arms.

Kay "did say, with respect to stockpiles, we were wrong, terribly wrong," Powell was quoted as saying. "But he also came to other conclusions that deal, I think, with intent and capability which resulted in a threat the president felt he had to respond to."

The secretary of state went on to say that "Saddam Hussein and his regime clearly had the intent -- they never lost it -- an intent that manifested itself many years ago when they actually used such horrible weapons against their enemies in Iran and against their own people."

Powell added that the Iraqi leader had kept in place the ability to produce weapons. "There's no question about that and there's nobody debating that part of the intelligence."

Iraq maintained the "technical infrastructure" that could "produce such weapons at a moment in time, now or some future moment in time," Powell said. "I think there's evidence that suggests that he was keeping a warm base, that there was an intent on his part to have that capability."

"If you look at my presentation from last year, I talk about intent," Powell said.

"I talk about the capability I think is there, the stockpiles, but a large part of the presentation is also what happened" and the unanswered questions about Iraq's weapons holdings.

Powell highlighted how chemical weapons had been found in Iraq after the 1991 Gulf War when he was chairman of the Joint Chiefs of Staff. "So it wasn't as if this was a figment of someone's imagination."

The secretary of state gave a robust defence of the Bush administration's decision to go to war, saying Saddam Hussein would have ramped up his weapons capabilities if left unchecked by the international community.

"I think that the international community wouldn't have kept them constrained," he said.

"There is absolutely no doubt in my mind that if Iraq had gotten free of the constraints and if we had gone through another year of desultory action on the part of the United Nations and when they were freed without threat... they would have gone to the next level and reproduced these weapons."

Powell said there was not one single word in his February 5 presentation to the Security Council that had not been "totally cleared by the intelligence community."

He also said that not only the Central Intelligence Agency, but other intelligence agencies and Britain had "suggested that the stockpiles were there."

He said his presentation last year had "reflected the best judgements of all the intelligence agencies ... There wasn't a word that was in the presentation that was put in that was not totally cleared by the intelligence community."

The secretary of state voiced confidence the American people would understand "with the body of evidence, that was the information and intelligence that was available to the president at that time, the president made a prudent decision."

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