Updated

A team of international experts is visiting Iraq to inspect mobile labs that the United States believes were part of a suspected biological weapons program, a top U.S. military commander said Monday.

Meanwhile, U.N. nuclear inspectors (search) were preparing to return to the country to conduct a damage assessment of Iraq's largest nuclear facility.

The Tuwaitha nuclear complex (search) was repeatedly looted in the early days of the war by nearby villagers who removed barrels believed to have stored radioactive materials. In many cases, the barrels were used to store drinking water, and some villagers have reported health problems that are being investigated by the U.S.-backed Health Ministry.

Mark Gwozdecky, spokesman for the Vienna-based International Atomic Energy Agency (search), said a small team would try to determine what happened to materials the agency had monitored at the site since the end of the 1991 Gulf War.

"The mission is limited to verifying Iraq's safeguards obligations," Gwozdecky said.

Inspectors will "determine what is missing and what it will take to recapture that material and ultimately repackage it and reseal it and secure the facility," he added.

Col. Tim Madere, a chief military officer for unconventional weapons with the Army's V Corps, said last week that 20 percent of the barrels the IAEA had been monitoring at Tuwaitha were missing. Madere confirmed Monday that the IAEA team would arrive in Iraq within days.

Another team of international experts invited by Washington to inspect the mobile laboratories arrived Saturday, he said.

"They are here working and will probably need a few days," Madere told The Associated Press.

The two labs already have been inspected by U.S. and British technical experts and a group of scientists from coalition countries.

Pentagon officials have said the discovery of the first trailer — seized at a checkpoint near the northern Iraqi city of Mosul on April 19 — could prove Iraq had active programs to produce weapons of mass destruction. The second trailer was found May 9 at al-Kindi, a former missile research facility in Iraq.

President Bush launched the war on March 20, in part, to rid Iraq of weapons of mass destruction.

Saddam Hussein's regime long insisted that Iraq had destroyed its unconventional weapons and programs years ago. U.N. weapons inspectors, who spent 3 months in Iraq just prior to the war, found no evidence to refute the Iraqi claims.

So far, U.S. weapons hunters have not uncovered any such weapons either, despite searches at more than 100 sites.

Barrels of processed uranium and several tons of natural uranium at Tuwaitha had been under IAEA monitoring before the war.

As reports filtered out of Iraq that the site was left unguarded by U.S. troops, then looted by villagers, the IAEA sharply criticized the U.S. handling of the facility and publicly pushed for its return.

Last week, the Pentagon relented after trying to keep out the same inspectors they blame for hurting America's case for the war.

But this time, the IAEA's return will be brief and limited by the United States. The team is expected to leave for Iraq by week's end and stay about 10 days.

"The IAEA was informed by the United States that at this stage, the occupying powers are responsible for the health and safety of the Iraqi people — including nuclear health and safety issues," Gwozdecky said.