The government has begun testing a computerized screening system that compares airline passengers' names with those on terrorist watch lists (search), a Transportation Security Administration (search) official said Thursday.

Called "Secure Flight," (search) it's meant to replace a plan that never got to the testing stage because of criticism that it gave the government access to too much personal information.

Testing of Secure Flight began Nov. 30. No announcement was made; TSA spokesman Justin Oberman disclosed its status when asked by The Associated Press.

The testing has not turned up any suspected terrorists. Oberman said the agency expects to wrap up the first phase of testing in a month.

"The technology is working, doing exactly what we wanted it to do," he said.

The TSA is testing data on passengers who flew domestic flights on U.S. airlines in June. The airlines, concerned about upsetting passengers, had refused to turn over the information, but the TSA issued a security directive ordering them to do so.

About 1.9 million passengers travel by air daily, and part of the test will see if the government's system can handle that much information.

The government has sought to improve its process for making sure terrorists don't get on planes since the Sept. 11 hijackers exposed holes in the system. Airlines now simply match passenger names against government watch lists of people considered threats.

Federal authorities don't disclose criteria for placing people on the lists, how many names are listed or any identities. In a number of well-publicized incidents, people with names similar to those on the lists were stopped from boarding planes. Among them was Sen. Edward M. Kennedy, D-Mass.

Marcia Hofmann, attorney for the Electronic Privacy Information Center, a Washington-based advocacy group, said many problems remain with the Secure Flight program.

"The redress process is still a question mark," Hofmann said. "The ability of individuals to access and correct information that is being used to make determinations about them is still at issue."

Oberman said the agency is working on a way for passengers to appeal if they think they've been wrongly identified as terrorists.

Under Secure Flight, the airlines would electronically transmit to the government passenger names as well as other identifying information. The government would then match that information with the terrorist watch lists; names on those lists are supposed to include biographical information.

The passenger information that's being tested is known as passenger name records, or PNR. It can include credit card numbers, travel itineraries, addresses, telephone numbers and meal requests.

Oberman said further testing will show whether the system can handle a surge of information during busy air travel periods. Name-matching software will also be fine-tuned, he said.

The TSA says Secure Flight differs from the previous plan because it does not compare personal data with commercial databases. Privacy advocates were concerned that doing so would allow the government to accumulate vast amounts of sensitive information about people who weren't suspected of breaking the law.

The agency said, however, it will test the passenger information "on a very limited basis" against commercial data to see if that could reduce the number of people who are confused with names on watch lists.

Before that happens, though, the Government Accountability Office must report to Congress on the TSA's plan to test the commercial data. That's expected by the end of March.

Oberman said he expects testing will be completed by then. However, it's unclear when Secure Flight will be implemented.