State Dept. Aides Eavesdropped on Calls : Investigation: Secret monitoring of some conversations came to light during probe of passport record searches. Ban on practice has been ordered.

The State Department said Friday that some telephone calls placed through its 24-hour-a-day operations center have been secretly monitored by note-taking officials, possibly in violation of laws concerning eavesdropping.

Acting Secretary of State Lawrence S. Eagleburger banned secret monitoring last month after department investigators discovered that former Assistant Secretary of State Elizabeth M. Tamposi had been overheard during the presidential campaign discussing a controversial search of now-President-elect Bill Clinton’s passport files as well as those of his mother and independent candidate Ross Perot.

Under Eagleburger’s new directive, operations center employees can listen in on phone calls only if one party to a conversation requests it. Government officials frequently direct subordinates to listen to their conversations, take notes and prepare summaries--a practice that is permitted under the new order.

Although State Department officials said most employees realized that calls could be monitored, some apparently did not. It is illegal under federal law to eavesdrop on telephone conversations without the permission of at least one party. There is no requirement in the law or in Eagleburger’s directive to inform the second party that a conversation is being overheard.

Department spokesman Richard Boucher said the FBI is investigating possible criminal violations.

“The operations center has no capability for taping phone calls, and they have no access . . . to telephone calls that are not placed through the (operations) center,” Boucher said.

Boucher said the State Department’s inspector general, Sherman Funk, discovered the secret monitoring as he was investigating possible wrongdoing in connection with the passport records searches during the presidential campaign. Boucher said Funk immediately informed Eagleburger and later briefed the FBI on the practice.

Funk is expected to issue his report on the matter next week, detailing any violations of law and departmental regulations.

According to a report by the staff of the House Foreign Affairs Committee, the State Department officials who combed through the files in a government records center in suburban Maryland apparently were searching for damaging information about President Bush’s election foes.

Tamposi, chief of the department’s consular bureau, which includes the passport office, was fired earlier this week. A former Republican fund-raiser and a political appointee at the department, she had not been expected to remain in the post after Clinton’s inauguration. She has issued a written statement denying wrongdoing.

Department officials refused to disclose the contents of Tamposi’s overheard conversations.