U.S. homeland security chief, Tom Ridge, says he will move to correct gaps in background checks of security screeners at the nation's airports. His comments came in a second day of testimony before a congressional panel which is seeking to learn how safe Americans are from terrorist threats.

In two appearances before the House Select Committee on Homeland Security, Mr. Ridge faced tough questions about reports many people were hired as airport "screeners" without thorough background investigations.

Those screeners are employed by the Transportation Security Administration (TSA), established in the wake of the September 2001 terrorist attacks. TSA is part of the Department of Homeland Security.

Recent news reports said 24 screeners at Los Angeles airport were found to have criminal records. A similar problem was discovered at New York's John F. Kennedy airport.

"Ideally, from the outset, we would have done a finger print-based check, a credit check, a variety of checks normally associated with government employment," said Mr. Ridge. "Given the number, and time constraints, it (the hiring process) was privatized and now we, over the past several months, have begun to use federal assets to again add another level of screening to that done by the private sector."

Hijackers who carried out the September 2001 terrorist attacks are thought to have used box cutters to take over commercial airliners crashed into the World Trade towers in New York City, and the Pentagon.

The fact that they were able to slip through airport security lent urgency to an accelerated effort to hire some 55,000 screeners for the TSA to meet a congressionally-mandated November 2002 deadline.

Mr. Ridge also faced questions about more blatant airport security problems.

Congressman Robert Andrews of New Jersey, cited examples of weaknesses at Philadelphia airport. "Everybody should walk through a metal detector before they get into any area of the airport that is sensitive," said Congressman Robert Andrews of New Jersey, citing examples of weaknesses at Philadelphia airport. "You have to, Mr. Secretary, we have to. And the idea that employees who have access to the tarmac are not walking through a metal detector is alarming. What's more alarming is the answer was, sort of classic answer you get from a government bureaucracy, which is well it's in the handbook, so it must OK."

These examples, from the largest international airport in his home state of Pennsylvania, hit home with Mr. Ridge, who pledged to fix the problem. "The time delay in responding, and the nature of the response, was unacceptable. I'm not going to try to explain it," he said. "It should be fixed. And I can't believe. I would like to see the interpretation of the policy that says keeping badges to give people access to airports after they've been terminated is part of the policy of TSA."

Overall, Mr. Ridge has been supportive of TSA employees, calling them dedicated and skilled. But under further questioning, he was forced to defend a decision, announced in April, to reduce by about 3,000 the number of screeners at airports.

A separate congressional hearing, at which the head of the Transportation Security Administration, James Loy, was scheduled to testify was postponed Thursday without explanation.