U.S. forces may have found banned chemical weapons stored in huge drums at a military training camp in central Iraq.

Pentagon sources told Fox News a prisoner of war gave U.S. forces information directing them to a specific site outside Karbala, near a camp described as a military facility, and that preliminary field tests on substances found at the site suggest they contain several banned chemical weapons, including deadly nerve agents and blister agents.

Maj. Michael Hamlet of the U.S. 101st Airborne Division said the nerve agents sarin and tabun and the blister agent lewisite appeared to be present at the site, Reuters reported.

A team of experts would carry out further tests as early as Tuesday, Hamlet said.

The chemicals were found at the camp in Albu Mahawish, between the central Iraqi cities of Karbala and Hilla, Reuters reported.

"If tests from our experts confirm this, this could be the smoking gun. It would prove [Saddam Hussein] has the weapons we have said he has all along," Hamlet said. "But right now we just don't know."

A Knight Ridder News Service journalist traveling with the 101st said initial tests of samples from the facility were inconsistent. Some tests did not indicate chemical weapons, while others indicated the presence of G-class nerve agents -- which include sarin and tabun -- and mustard gas -- a blistering chemical first used in World War I.

The correspondent, Tom Lasseter, also reported that he and several soldiers were decontaminated after some of the soldiers felt ill while searching the compound. Officials at the Pentagon said they did not have any information about anyone getting sick.

Although officials were quick to point out that past field tests have produced false positives, one senior defense official told Fox News that "this is a fair amount of stuff, many-gallon drums of a variety of different agents, blister and nerve ... and initial reports indicate it is the real deal."

Defense Secretary Donald Rumsfeld, in a news briefing, downplayed the report, saying the Pentagon would have to take a good look at it before commenting on a media report.

"Almost all first reports we get turn out to be wrong," he said. "We don't do first reports and we don't speculate."

Agence France-Presse reported that the substances had turned out to be pesticides, but Rumsfeld said it could take several days to get a positive identification of the chemicals.

Former U.N. weapons inspector Tim Trevan told Fox News that it would be no surprise if final testing did in fact conclude the substances were banned chemical agents.

"Obviously, they have the wherewithal to produce this stuff," Trevan said, but cautioned that more definitive testing needed to be done.

"These are all agents which we know they produced in the past, it's associated with a munition which we know they've used for sarin and tabun in the past … and also it's in the area we were expected to find it," he said, referring to the so-called "red zone" -- the 50-mile perimeter around Baghdad where coalition military officials think Saddam may have authorized the use of chemical weapons.

Retired U.S. Army Cmdr. Sgt. Steve Greer said he is "cautiously optimistic" that this may be the smoking gun needed to prove to the international community that Iraq does, in fact, have banned weapons of mass destruction.

Iraq acknowledged making 3,859 tons of sarin, tabun, mustard and other chemical weapons, though U.N. weapons inspectors suspected Iraq could have made much more.

Iraq used mustard and sarin against Iran during the 1980-88 Iran-Iraq war and is believed to have used the chemicals against Kurdish Iraqis. Iraq began producing sarin in 1984 and admitted to possessing 790 tons of it in 1995.

Sarin is a colorless and odorless gas and is lethal in doses as small as half a milligram. Death may occur within one to 10 minutes of inhalation exposure to even a small amount of sarin.

Sarin is most known for the March 1995 terrorist attack by the Aum Shinrikyo religious cult, when members released the gas at several points in the Tokyo subway system, killing 11 and injuring more than 5,500.

Tabun is a clear, colorless and tasteless liquid with a slightly fruity odor, and is lethal, although only about half as toxic as sarin. Lethal respiratory dosages kill in one to 10 minutes, and liquid in the eye kills almost as rapidly. If skin absorption is great enough, death may occur in one to two minutes, or it may be delayed for one to two hours.

Fox News' Major Garrett, Liza Porteus and Mike Tobin and The Associated Press contributed to this report.