A company that allegedly hired criminals to staff security checkpoints at Philadelphia International Airport admitted in court documents that it failed to check backgrounds of employees nationwide.

Atlanta-based Argenbright Security Inc. pleaded guilty last year in Philadelphia to violating federal rules. It paid a $1 million fine, was placed on probation and agreed to conduct background checks.

Argenbright said in documents filed Friday that it had not performed the required checks as of April, a year after being placed on probation.

The documents are part of a settlement with federal prosecutors who filed a motion last week alleging that the background checks weren't being done. The settlement awaits a judge's approval.

Prosecutors said inspectors in the past year found 18 guards with convictions ranging from drug possession to burglary and resisting arrest. Generally, convicts are barred from security jobs at U.S. airports.

In the proposed settlement, Argenbright agreed to fingerprint all employees, extend its probation from three to five years, and regularly audit billing records and file compliance reports.

"This isn't designed to fix every problem the company has," said Assistant U.S. Attorney John Pease. "This is designed to address solely their failure to comply."

An Argenbright spokesman declined comment Friday.

The company's 25,000 employees work at all major U.S. airports. Between August and October, the company said it did perform background checks in 12 of the airports where it operates.

Argenbright handles passenger checkpoints, baggage and other services for American and United airlines at Dulles International Airport near Washington and Newark International Airport in New Jersey. Two of the planes hijacked Sept. 11 had departed from those airports.

The company also provides services at Boston's Logan Airport, but does not work for United or American, the airlines whose planes were hijacked there and crashed into the World Trade Center.