The United States' high-tech system for detecting biological attacks has flaws, and it remains to be seen whether upgrades will solve them, experts say.

The Department of Homeland Security's BioWatch system of air samplers has experienced numerous false alarms since first being deployed in 2003, the Los Angeles Times reported Saturday. The newspaper said its investigation found the system not only has produced dozens of false alarms in Los Angeles, Detroit, St. Louis, Phoenix, San Diego and the San Francisco area, but that confidential government results and computer modeling determined BioWatch can't be depended upon to detect a real attack.

The Times said state and local health officials have exhibited no confidence in BioWatch, having never ordered evacuations or distributed emergency medications when a positive reading has occurred.

While the cause of the false alarms has not been pinpointed by federal officials, the Times said scientists familiar with the system say the problem appears to be the equipment's inability to tell the difference between dangerous pathogens unleashed by terrorists and similar, naturally occurring germs that do not pose a threat.

"I can't find anyone in my peer group who believes in BioWatch," said Dr. Ned Calonge, chief medical officer for the Colorado Department of Public Health and Environment from 2002 to 2010.

"The only times it goes off, it's wrong. I just think it's a colossal waste of money. It's a stupid program."

Several people who attended a November meeting said officials from the Centers for Disease Control and Prevention told White House aides they would not send medicine to the site of a supposed attack based solely on a BioWatch warning. Independent confirmation would be necessary, they said.

Homeland Security officials say the system is working because it is detecting organisms, even if of a benign nature, and the experience is being used to develop a better product. They have told Congress updated technology, dubbed Generation 3, will make BioWatch better and less expensive to operate. BioWatch has cost a billion dollars so far, and Generation 3 is expected to run about $3.1 billion for the next five years. The Obama administration has yet to award a multiyear contract for the program Dr. Alexander Garza, Homeland Security's chief medical officer, calls "imperative to saving thousands of lives."

Questions remain about just how effective the new technology will be, with the Times reporting a confidential Homeland Security analysis prepared in January found "failures were so significant" the department had proposed that Northrop Grumman Corp., which is in the running for the Generation 3 contract, make "major engineering modifications."

Department spokesman Peter Boogaard told the Times "all precautions necessary" would be taken "to minimize the occurrence of both false positive and false negative results."

Northrop Grumman officials told the newspaper some test results had led to improvements.

"We had an issue that affected the consistency of the performance of the system," said Dave Tilles, the company's project director. "We resolved it. We fixed it. … We feel like we're ready for the next phase of the program."