"Launching preemptive strikes on the basis of intelligence gathered by secret services is something to which we should pay careful attention," Blix told Le Monde, in a veiled criticism of the US-British invasion of Iraq.

"It's not the first time that force has been used on the basis of intelligence that turned out to be erroneous," he added.

Blix was referring to claims by Washington and London that Baghdad was harboring weapons of mass destruction, their main justification for the war to topple Saddam Hussein. To date, no such weapons have been found.

In Iraq, "a war started on the basis of intelligence reports. We do not yet know if they were correct. But it raises the question: on what basis can a war be launched?" Blix asked.

Blix, who is to retire on June 30 after more than three years as chairman of the UN Monitoring, Verification and Inspection Commission (UNMOVIC), reiterated that his inspectors never found proof that Iraq has banned weapons.

"We never said that we had evidence of the existence of weapons of mass destruction in Iraq, but rather that we had evidence that unanswered questions remained" about Baghdad's weapons programs, he told Le Monde.

In an interview published Wednesday in the London daily The Guardian, Blix lashed out at "bastards" in Washington "who planted nasty things in the media" in a bid to undermine his efforts.

But in the interview with Le Monde, Blix denied that he was referring to members of the US administration, instead pointing the finger at former weapons inspectors and a former Swedish prime minister, whom he did not name.

He explained that his critics had slammed his work when he served as head of the International Atomic Energy Agency in the early 1990s.

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