Brigadier General Vincent Brooks, addressing a press briefing here at the US military's forward command base, also referred to reports that boxes containing powder had been located in Iraq but provided no details.

"The report of the powder in boxes -- we have just recently heard about but we dom't have any details that are factually based ... at this time," he said.

But during a raid by US special forces in western Iraq, he continued, bottles labelled as chemical agents were discovered in a building.

"These bottles were samples," according to Brooks, with one of them marked as a chemical agent that was developed in the 1940s.

"Some of these were taken away and testing is ongoing."

But Brooks added that an initial investigation did not suggest it was a site for the manufacture of weapons of mass destruction.

"What we discovered in the west ... where a special operations raid was ongoing, was a building which we think now was probably an NBC (nuclear, biological, chemical) training school," he told reporters.

"Our conclusion at this point is that it's not a WMD (weapons of mass destruction) site per se, and in this case it proves to be something far less than that."

Iraq has denied US and British allegations that it is harboring banned nuclear, biological and chemical weapons, and invading US and British troops have so far failed to turn up any such weaponry in their 15-day-old campaign.

But US commanders remain convinced that such stocks exist and have pointed to a number of discoveries -- such as protective clothing and apparatus for use in a chemical attack -- that they say suggest weapons of mass destruction are indeed in Iraq's possession.

Brooks on Friday recalled, for example, that US troops had discovered atropine injectors, which are used by troops as an antidote to chemical weapons exposure.

As a result of such finds, US officers insist that Iraq has both the means and the will to engage in chemical warfare and are confident chemical weapons will be uncovered once Saddam Hussein is driven from power and scientists can talk freely.

But a field intelligence officer with the 101st Airborne Division's Aviation Brigade said Thursday the threat of an Iraqi chemical or biological attack against coalition forces had become "negligible."

"Now that we have penetrated Baghdad's outer ring, the likelihood (of a chemical or biological attack) is negligible," said Captain Adam Mastrianni.

"We thought if he was going to use chemicals, the first major town he was going to use them in was in Karbala," a major Shiite community less than 100 kilometres (60 miles) south of Baghdad, Mastrianni said.

"The next major zone, was when we (coalition troops) penetrated outer Baghdad," he said, defining the area as within 30 kilometres (20 miles) of the capital.

"Now the 3ID (3rd Infantry Division) is in Baghdad and no chemicals have been used," he added.

"We think that quite frankly, even if Saddam Hussein is in control, which is still debatable, he's paralysed by the fact he knows he will be prosecuted over warcrimes."

SPACE.WIRE