The U.S. Postal Service is expanding the test of a system to detect any new anthrax attack, 18 months after anthrax-by-mail terrorism killed five.

The search for whoever sent the deadly spores, meanwhile, is going slowly.

The new biological detection system has been tested for several months in Baltimore and will now go to 14 other cities for evaluation, including Dulles and Capitol Heights, Tom Day, postal vice president for engineering, said yesterday.

"We have carefully reviewed its results and we are now confident that it is working successfully," Day said at a news conference at USPS headquarters.

The system uses rapid DNA testing to look for anthrax and can be adapted to test for other biological hazards, he said. Across town, cleanup was being completed at the contaminated Brentwood postal facility where anthrax spore-laden mail addressed to two senators in October 2001 sickened several postal workers and killed two.

The new testing system will not disrupt the movement of mail, Day said, producing results in as little as 30 minutes.

The tests get under way June 1 and run for 30 days.

The agency will then review the results to determine whether to install the equipment across the country.

The anthrax detectors are attached to the first pieces of automated equipment that handle mail in sorting offices. A hood is placed over the slot where the mail moves and the air in that hood is continuously sampled and tested.

In months of testing in Baltimore, the machine detected anthrax whenever samples were sent through it, Day said.

Day declined to state the cost of the new machines, but he did say the postal board of governors approved the program. Board approval is required for any capital spending of more than $10 million.

The system was developed with the cooperation of military experts, the National Institute of Standards and Technology, the Department of Agriculture, the Centers for Disease Control and Prevention and Johns Hopkins University.

The other test sites are Albany, N.Y.; Edison, N.J.; Manasota, St. Petersburg and Tampa, Fla.; Midland, Tex.; Los Angeles; Tacoma, Wash.; Rockford, Ill.; Lancaster and Pittsburgh, Pa.; and Cleveland.