Mohamed ElBaradei, director general of the International Atomic Energy Agency (IAEA), said the watchdog had been proven correct and under no political influence.

"The lesson I take from that is that the international community should listen to us more carefully in the future" before deciding to use force, he told the Japan National Press Club.

UN arms inspectors who found no evidence of weapons of mass destruction left Baghdad shortly before the US-led invasion of Iraq in March 2003.

In a report of more than 1,000 pages Wednesday, chief US arms inspector Charles Duelfer concluded that Saddam destroyed most of his chemical and biological weapons after the 1991 Gulf War and that his nuclear program had "progressively decayed".

ElBaradei said it was a "relief" to see that the IAEA inspection had helped with disarmament before the war and vowed that UN inspectors would go back to Iraq once the security situation improved.

ElBaradei, 62, was on a four-day visit to Japan. He leaves Saturday after talks with senior Japanese officials.