Telephone companies have cut off FBI wiretaps used to eavesdrop on suspected criminals because of the bureau's repeated failures to pay phone bills on time.

A Justice Department audit released Thursday blamed the lost connections on the FBI's lax oversight of money used in undercover investigations. In one office alone, unpaid costs for wiretaps from one phone company totaled $66,000.

In at least one case, a wiretap used in a Foreign Intelligence Surveillance Act investigation "was halted due to untimely payment," the audit found. FISA wiretaps are used in the government's most sensitive and secretive criminal and intelligence investigations, and allow eavesdropping on suspected terrorists or spies.

"We also found that late payments have resulted in telecommunications carriers actually disconnecting phone lines established to deliver surveillance results to the FBI, resulting in lost evidence," according to the audit by Inspector General Glenn A. Fine.

More than half of 990 bills to pay for telecommunication surveillance in five unidentified FBI field offices were not paid on time, the report shows.