Washington -- Troops from the U.S. Army's 101st Airborne Division - - stationed in northern Iraq and headquartered in Mosul -- have found what military authorities believe may be a second mobile biological weapons laboratory, says the division commander.

"The suspected mobile biological agent production lab found on 9 May in our area was found by one of our infantry units during operations at the al-Kindi Rocket and Missile Research and Development Center," Major General David Petraeus said May 13 during a briefing from Mosul. "Our own chemical section looked at the trailer and confirmed it as a trailer that was very close to identical to the first trailer that was found by Special Forces southeast of here last week."

Petraeus said he spoke with experts May 13, and they have a "reasonable degree of certainty that this is in fact a mobile biological agent production trailer."

The trailer contains a 5,000 pounds-per-square-inch compressor, a 2,000-liter reactor vessel, a small feed tank, a 3,000-liter water tank and a water chiller, he said. , he said.

"It had a manufacture date of 2003 and a serial number of 2," Petraeus said, adding that the plate from the first trailer found April 19 by Army Special Forces had a manufacture date of 2002 and a serial number of 1.

The trailer found May 9 has been moved to Baghdad International Airport for security and for further examination by a team of experts coming from the United States, he said.

Petraeus also said that, based on a preliminary examination by his chemical experts, the lab had not been completed. "Several welds were not finished, and shipping plugs were still in place", he noted, adding that a water pump, forward air compressor, canvas cover and some of the piping had been looted.

The trailer found April 19 by U.S. troops outside the northern Iraqi city of Tall Kayf is also undergoing extensive testing and evaluation in Baghdad. At a special Pentagon briefing May 7, Stephen Cambone, the under secretary of defense for intelligence, said that it was seized at a Kurdish checkpoint in northern Iraq. It had been freshly painted in a military camouflage pattern and thoroughly washed with a caustic solution to hide the work conducted in the lab.

"The experts have been through it. And they have not found another plausible use for it," Cambone said. "So while some of the equipment on the trailer could have been for purposes other than biological weapons agent production, U.S. and U.K. tactical experts have concluded that the unit does not appear to perform any function beyond ... the production of biological agents.''

U.S. intelligence officials have said they believe Iraq had 18 mobile chemical and biological laboratories, but finding them will be a laborious process. Cambone said that, for example, U.S. troops found an Iraqi fighter jet that had been literally buried in the desert to hide it from coalition troops, an indication of Iraq's extensive efforts at deception.