Meanwhile, Washington again insisted that Iraq’s alleged and so-far elusive weapons of mass destruction, the main justification of launching its invasion, would be found, as Iraqis protested over possible contamination after looting at the country's main nuclear site.

U.N. inspectors, who Saturday began their first postwar inspection of Iraq’s largest nuclear plant, have said thousands may have been poisoned when it was looted in the wake of the U.S.-led invasion two months ago.

Worried neighbors of the Tuwaitha plant outside Baghdad demonstrated at the site Sunday to demand that the U.N. press the United States to tackle their plight.

"U.S. forces should be investigated for what they have done here," said one slogan carried by half a dozen residents, angry that they may have been poisoned by looting that U.S. troops failed to prevent.

There are fears that local farms as well as the water supply may have been contaminated in the postwar chaos.

The United States meanwhile said it remained convinced that Iraq’s alleged weapons of mass destruction would be found, despite growing doubts that they exist.

"I believe we will find them," U.S. national security adviser Condoleezza Rice told NBC television.

"I don't see how anyone can say that there wasn't a true danger here, when the (U.N.) weapons inspectors themselves were saying that there were thousands of tons of missing VX, missing anthrax, missing sarin gas," she said.

Secretary of State Colin Powell also stood by his February statement to the U.N. Security Council, in which he detailed U.S. claims that Iraq was hiding weapons of mass destruction.

"Not only have I been studying this for many, many years, but, as I prepared that statement, I worked very closely with the director of central intelligence, George Tenet," Powell told the "Fox News Sunday" program.

"There can be no question there were weapons before the war," Powell insisted.

Chief U.N. weapons inspector Hans Blix said in an interview with the BBC on Thursday that his teams followed up U.S. and British leads at suspected sites across Iraq, but found nothing when they got there.

The U.S.-led coalition also on Sunday urged Iraqis to denounce those carrying out near-daily attacks on its troops and local police.

"The coalition will not tolerate attacks against its forces because they target not only its men but the Iraqi people," occupation radio said.

"If you have information on people taking part in these attacks, pass it on immediately. Coalition forces and the Iraqi police are actively working to make Iraq more stable and safe," the radio said.

"If you refuse to give information on these criminal acts, Iraq will become a dangerous country for everyone."

This came as the U.S.-led occupation authorities broadcast a fresh appeal to Iraqi scientists to come forward Sunday as a new 1,300-strong task force arrived to step up the hunt for Saddam Hussein's alleged banned arsenal amid mounting doubts.

"We know there are Iraqi scientists, soldiers and officials of the Baath party who have information about the weapons of mass destruction produced by the old regime," occupation radio said.

"Even if you think the information is worthless, or you believe that the coalition already knows whatever information you have, don't hesitate to come forward."

The governments of both U.S. President George W. Bush and his staunch British ally Prime Minister Tony Blair have been on the defensive as U.S.-led forces in Iraq have yet to find the banned weapons.