US defense officials on Monday said preliminary tests showed that barrels found at a military site near the central Iraqi town of Karbala contain chemical agents.

But Major General Stanley McChrystal, vice director for operations at the US Joint Chiefs of Staff, told a news briefing there were some positive field tests "but they were mixed."

"We have taken samples out to get definitive testing," he said. "It is something we're looking at closely, but no hard finding."

According to US news reports, US Marines said they found a warehouse near Baghdad's main airport containing missiles loaded with warheads filled with mustard gas and sarin.

McChrystal said he had seen a news report on the rocket rounds. "But I have seen nothing in official reports that would corroborate that."

SPACE.WIRE