The FBI, through electronic eavesdropping devices, intercepted conversations Mayor Marion Barry had with D.C. contractor John B. Clyburn and city official David E. Rivers, city officials said yesterday.

The officials said Barry has received two letters from federal prosecutors informing him that his conversations with Clyburn and Rivers had been overheard. The intercepts resulted from bugs on Clyburn and Rivers' phones and in Clyburn's office. Prosecutors previously have said that they have not bugged Barry's phones.

The U.S. attorney's office, following the conclusion of court-ordered electronic surveillance, is required by law to notify anyone whose conversations have been intercepted.

In the past few days, prosecutors have notified numerous city officials, contractors and associates of Rivers and Clyburn of the wiretaps and room bug. Late Thursday, Barry said through a spokesman he did not know of any notification from prosecutors about his own conversations. One city official said Barry apparently did not receive the letters until yesterday.

"The mayor has not seen the letters themselves but he understands they were delivered to his house," said John C. White, the mayor's spokesman.

The notification does not imply that prosecutors suspect wrongdoing by Barry or anyone else whose conversation was overheard.

Federal authorities obtained a court order to tap Rivers' home and office phones between March 6 and May 5 as part of an undercover FBI investigation centering on the award of city contracts. They also tapped eight phone lines and the office intercom at Clyburn's business and planted a bug in Clyburn's office for a 10-month period ending Feb. 13.

In another development in the probe of alleged corruption, Gladys Baxley, a former high-ranking official with the Department of Human Services, testified for more than two hours yesterday before a federal grand jury investigating whether Rivers steered contracts to his friends.

Baxley resigned about three months ago as administrator of the agency's mental health services division and is now a consultant. She said yesterday that she testified about JMC Associates Inc., a firm that received a $216,739 contract last year to treat the mentally ill.

One agency official has told the FBI that Baxley originally objected to the cost of the contract but changed her mind after talking to Rivers, according to sources. The contract, designed to provide a cheaper alternative to hospitalization, ended up costing the city nearly three times as much as St. Elizabeths Hospital charges.

Baxley is expected to testify again Friday.