WASHINGTON, Oct. 18 (UPI) -- U.S. airport security screeners failed to detect fake bombs 60 percent of the time in Los Angeles and Chicago, USA Today reported Thursday.

A classified report seen by the newspaper said most undercover agents posing as passengers were able to get through security last year with simulated bombs or components under their clothes or in carry-on bags.

The tests of Transportation Security Administration workers were done at airports in Los Angeles, San Francisco and Chicago.

San Francisco screeners work for a private company and missed about 20 percent of 145 attempts, the internal report said.

However, TSA screeners in Los Angeles missed 75 percent of fake bombs in 70 tests and Chicago TSA screeners missed 60 percent of 75 tests, the report said.

In the late 1990s, the Government Accountability Office said tests showed screeners missed about 40 percent of fake bombs, the newspaper said.