Air Force officials may have violated federal laws and military rules when they bought 100 commercial versions of the detectors and supplied them to commanders in the Middle East while knowing that the manufacturer's tests showed the detectors did not work well in hot areas or under battle conditions.

Moreover, officials did not wait for other necessary tests, including some at Utah's Dugway Proving Ground, according to a Defense Department Inspector General report.

The Pentagon has ordered the Air Force to stop using the 100 detectors that were purchased and to send them to military testers who are working to improve them.

The documents say the military began developing a hand-held chemical arms detector after the first Iraq war, and British Aerospace Systems was chosen as the contractor for a "joint chemical agent detector" or JCAD. After the Sept. 11, 2001, terrorist attacks, that company began marketing a commercial version called the JCAD ChemSentry.

The inspector general report says Air Force Central Command overseeing the Middle East erroneously felt the commercial unit had advantages over detectors it was already using.

At the command's urging, the military's JCAD Program Office brought 100 of the commercial detectors. The report says that agency knew the detectors did not meet its requirements, based on the manufacturer's own testing, but thought they worked well enough to be of use.

When a request for more units was submitted, the Pentagon said it would allow the purchase only if tests proved the JCAD was better than existing detectors.

The tests found that, among many problems, the detectors did not perform well enough in identifying when chemical agents were present, the report says.