Airlines are not complying with government orders issued after last month's terrorist hijackings to scan checked baggage for bombs, the Transportation Department's inspector general says. 

The Federal Aviation Administration ordered broad and partly secret safety measures be put in place before allowing flights to resume after the Sept. 11 attacks.

But in checks at seven of the nation's 20 highest-risk airports over the past week, the inspector general found widespread noncompliance with orders to run all bags through sophisticated bomb detection machines.

"At most of the machines we observed no bags were searched," Kenneth M. Mead told a House subcommittee Thursday.

A spokesman for the Air Transport Association, a trade group for the airlines, disputed the finding. ``Our carriers are doing what they are instructed to do by the FAA,'' said Michael Wascom.

Manufacturers of X-ray detection devices agreed, saying major changes were needed in training airport screeners.

"The current screening process is much the same today as it was four weeks ago, offering a false sense of security to the flying public," said Peter Williamson, vice president of Rapiscan Security Products Inc. of Hawthorne, Calif.

Ralph Sheridan, president of Billerica, Mass.-based American Science & Engineering Inc., estimated that only one in every 10,000 bags checked on domestic flights is screened.

"We are here today because we have lost the public trust. ... These attacks were not the result of a failure in the system, but rather a system designed for failure," Sheridan said.

As part of broad security measures ordered after the Sept. 11 terrorist hijackings of four airliners, the FAA directed carriers to make continuous rather than part-time use of their high-tech bomb-detection machines that used CAT-scan technology. For security reasons, Mead and the FAA would not disclose which airports or airlines were found unresponsive to that order.

FAA Administrator Jane Garvey said in an interview she had just learned of the inspector general's findings and needed to examine them further.

"We need to know more about it," she said. "There's also a question ... if the term 'continuous' is too ambiguous. We have required that it be continuous and we are enforcing it."

Rep. John Mica, R-Fla., chairman of the House Transportation aviation subcommittee, accused the FAA of being negligent in failing to use the best aviation security technology.

"The U.S. Customs Service has had technology which can detect plastic knives and other weapons deployed since 1999. Why is the FAA so far behind the curve?" he said.

Before the FAA order, the million-dollar-plus bomb detecting machines were used only selectively — largely based on responses to a computerized passenger profiling system that has been used primarily on international flights, and for passengers lacking proper identification or failing a security quiz.

The FAA has spent $441 million for 164 of the machines, most of which were installed at nearly 50 airports for use by 20 airlines. About 20 machines remain idle in a warehouse but are to be put to use in coming months.

James F. O'Bryon, deputy director of the Pentagon's live fire testing program, said FAA security chief Michael A. Canavan had told him the machines must test for nearly 100 different types of explosives.

But as of July, the latest month for which figures are available, the machines screened an average of only 350 bags per day, well below their capacity to screen 150 bags an hour, Mead said.

He said air carriers were reluctant to increase their use because it was feared that passengers would not put up with the inconvenience.