"It's going to be very embarrassing when it turns out they have nothing to declare," said Eugene Betit, a former defense intelligence analyst who belongs to Veteran Intelligence Professionals for Sanity (VIPS), formed in January to speak out on the use of intelligence to justify the war.

Another, former CIA station chief Ray Close, said: "I'm hoping they will be embarrassed into acknowledging a role for some independent body. And who could it be but the UN?"

As the "smoking gun" continued to elude US sleuths in Iraq, chief UN weapons inspector Hans Blix called for experts to return to the country to determine whether the weapons allegations -- the main justification for going to war -- had any foundation.

US Secretary of State Colin Powell said Thursday he was "reasonably sure" that proof will be found.

"We are quite confident of our intelligence," he told Jim Lehrer of PBS public television.

"There was a huge intelligence collection effort with all of our agencies working together to come up with the body of knowledge that we took to the UN, and that we had been presenting before the world for a long period of time," he said.

Adding to the pressure, Russia, a veto-wielding member of the UN Security Council, said it would not support the lifting of UN sanctions against Iraq unless UN inspectors confirmed the absence of weapons of mass destruction.

But Washington has so far rejected such calls, and US Defense Secretary Donald Rumsfeld on Thursday sought to deflect concerns that evidence could be planted.

"The (US search) teams have been trained in chain of control, really like a crime scene," Rumsfeld told Pentagon staff.

He said: "They will have people with them who will validate things, they will have the ability to take pictures, and to make sure that the control over any piece of evidence is as clear as it possibly can be."

Rumsfeld warned however: "That will not stop certain countries, and certain types of people from claiming, inaccurately, that it was planted."

Retired CIA intelligence analyst and VIPS member Ray McGovern told AFP: "Some of my colleagues are virtually certain that there will be some weapons of mass destruction found, even though they might have to be planted.

"I'm just as sure that some few will be found, but not in an amount that by any stretch would justify the charge of a threat against the US or anyone else."

He added: "Even if the planting were discovered by and by, they'll say, 'ok, the weapons were planted -- fine.'"

McGovern said he was alluding to a remark by Powell after it emerged that a letter purporting to show that Iraq had sought to procure uranium from Niger -- a key argument in the case for war and cited in President George W. Bush's January 28 State of the Union address -- was a forgery.

Powell told NBC: "It was the information that we had. We provided it. If that information is inaccurate, fine."

VIPS, made up of 25 former intelligence officials in the CIA, State and Defense Departments, Army Intelligence and FBI, made their first public statement on February 5, critiquing Powell's presentation before the UN Security Council seeking an international mandate for the war.

"Never before has a group of veteran CIA graduates -- all cum laude -- gotten together to critique the government," McGovern said.

CIA spokesman Tom Crispell, asked for comment on the former officials' remarks Thursday, said: "They're criticizing policy, not intelligence."

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