The government on Friday ordered airlines to turn over personal information about passengers who flew within the United States in June in order to test a new system for identifying potential terrorists.

The system, dubbed "Secure Flight," will compare passenger data with names on two government watch lists (search), a "no fly" list (search) comprised of people who are known or suspected to be terrorists, and a list of people who require more scrutiny before boarding planes.

"Secure Flight represents a significant step in securing domestic air travel and safeguarding national security information, namely, the watchlists," the Transportation Security Administration (search) said in a notice announcing the order.

Currently, the federal government shares parts of the list with airlines, which are responsible for making sure suspected terrorists don't get on planes. People within the commercial aviation industry say the lists have the names of more than 100,000 people on them.

The order follows a 30-day period during which the public was allowed to comment on the Secure Flight proposal. About 500 people commented on the plan; the overwhelming majority opposed it, saying it would invade their privacy and infringe on their civil liberties.

An airline industry representative said the carriers, which support the plan, are studying the order.