Major Ross Coffman, public affairs officer for the US army's 3rd Infantry Division, said the site was near the city of Hindiyah, about 100 kilometers (60 miles) south of Baghdad but would give no details.

"We are talking about finding a site of possible weapons of mass destruction," Coffman told reporters. "It could be a smoking gun."

Coffman said only that the site was some sort of facility. "It's not something that there's a cloud of gas everywhere," he said.

The US group Knight-Ridder Newspapers reported earlier Monday that US soldiers had evacuated an Iraqi military compound in the same area after tests detected the presence of sarin, a powerful nerve agent.

It said the test was conducted by a mobile laboratory after more than a dozen soldiers from the 101st Airborne Division guarding the compound came down with symptoms including vomiting, dizziness and skin blotches.

Officials at the US Central Command in Qatar refused to comment on the report.

SPACE.WIRE