WASHINGTON — The FBI acknowledged yesterday that it checks records of telephone calls made by government employees as part of criminal investigations of leaks of classified information, but the bureau denied that it routinely tracks calls made to and by reporters.

The bureau typically opens a leak investigation after receiving a referral from the Justice Department, spokesman Bill Carter said.

"The FBI will take logical investigative steps to determine if a criminal act was committed by a government employee by the unauthorized release of classified information," Carter said. "In such cases, investigators may examine the telephone records of government agencies."

Carter said a report published on ABC News' Web site left a misleading impression that authorities are tracking reporters' calls in an effort to root out confidential sources. The ABC story said the government, in an effort to trace leaks, was "tracking the phone numbers" that reporters call.

"Where the records of a private person are sought, they may only be obtained through established legal process," Carter said.

The FBI can seek warrants and subpoenas from judges and grand juries, either through traditional courts or a secret court established for espionage and terrorism investigations. The bureau also has the power to seek subscribers' telephone and Internet records without approval of a judge or grand jury in espionage and terrorism cases by issuing a National Security Letter.

The FBI sought information last year on 3,501 U.S. citizens and legal residents through those letters, the Justice Department said last month.

Ongoing government investigations are attempting to determine who leaked the name of CIA operative Valerie Plame in 2003 as well as the existence of the National Security Agency's warrantless eavesdropping program last year.