"He will soon be a free man again," a Security Council diplomat said, noting that Blix retires after more than three years as chairman of the UN Monitoring, Verification and Inspection Commission (UNMOVIC) on June 30.

"He has had enough of being the target of insinuations and wants to get a lot things off his chest", the diplomat said.

In an interview published by the London daily The Guardian, Blix said some members of the US administration had set out to undermine him, especially in the months leading up to the invasion of Iraq on March 20.

"There are bastards who spread things around, of course, who planted nasty things in the media," he said, adding: "Not that I cared very much."

UN Secretary General Kofi Annan has named Blix's deputy, Demetrius Perricos, as acting head of UNMOVIC "pending a Security Council decision on future arrangements".

The decision tacitly acknowledges that the United States, and the Pentagon in particular, is in no hurry to let the UN inspectors back into Iraq.

Blix, a former foreign minister of Sweden, told The Guardian he was convinced there were people in the administration of US President George W. Bush "who say they don't care if the UN sinks under the East River, and other crude things."

Rather than seeing the UN as a collective body of decision-making states, Washington viewed it as an "alien power, even if it does hold considerable influence within it," Blix said.

"By and large my relations with the US were good," Blix said, but he added that as the war against Iraq loomed, Washington "leaned on" his inspectors to produce more damning language in their reports.

Set up in December 1999, UNMOVIC was unable to work in Iraq until late November last year, as the regime of Saddam Hussein buckled to the mounting threat of US military action.

Although they were only able to complete 15 weeks of inspections before having to withdraw on the eve of the invasion, the UN team carried out 731 inspections at 411 sites suspected of containing chemical or biological weapons.

To the mounting frustration of Pentagon officials, Blix repeatedly provided cautious reports to the Security Council, noting that no evidence had been found to prove that Iraq had resumed production of banned weapons.

Last week, in an interview with the BBC, Blix hit back at his critics, saying they had provided him with inadequate intelligence tips.

"I thought, my God, is this is the best intelligence they have and we find nothing, what about the rest?" he said.

Driving home the message in an interview with ABC television on Wednesday, Blix said that with the billions of dollars' worth of sophisticated surveillance at their disposal, the US and British forces currently scouring Iraq "should have done better".

WAR.WIRE