Federal prosecutors obtained court orders to wiretap the office phone of D.C. businessman John B. Clyburn for nine months and the home and private office phones of city official David E. Rivers for two months, according to letters notifying individuals whose conversations were intercepted.

The prosecutors also obtained a court order to plant electronic surveillance devices in Clyburn's office during the course of an investigation into alleged D.C. government corruption, the letters from the U.S. attorney's office said.

City government sources identified five former or current city officials who were notified in letters during the past week that their conversations were intercepted: Public Works Director John E. Touchstone; former city administrator Elijah B. Rogers; Personnel Director Theodore Thornton; Employment Services Director F. Alexis H. Roberson, and George Thomas, controller for the mayor's office. Deputy Mayor for Economic Development Carol B. Thompson declined to comment last night on reports that she also received a letter.

John C. White, press secretary to Mayor Marion Barry, said Barry had not received a letter as of late yesterday.

The U.S. attorney's office, which sent the certified letters to numerous city businessmen and city officials, is required by law to notify anyone whose conversation was overheard. Though the letters said the conversations "may be the subject of future court action," the notifications are not meant to imply that the prosecutors suspect any wrongdoing by the person to whom the letter was sent.

The letters said Rivers' private city government line and his home phone were wiretapped from March 6 to May 5.

Seventeen days later, U.S. Attorney Joseph E. diGenova announced the end of a 17-month undercover FBI probe into city contracting.

Rivers, former head of the Department of Human Services, has been detailed to another assignment from his current post as secretary of the District of Columbia.

Electronic devices also were planted on the eight phone lines of Decision Information Systems Corp. from May 2, 1986, to Feb. 13, 1987, according to individuals who received the letters. Clyburn formerly controlled DISC and Data Processing Institute, which shared DISC's offices at 1425 K St. NW.

Authorities also placed an electronic device in Clyburn's private office in the suite and obtained a court order to tap the intercom there.

It could not be determined yesterday whether FBI agents also tapped the phone of convicted cocaine dealer Karen K. Johnson or developer T. Conrad Monts, both of whom are believed to be major figures in the ongoing inquiry into alleged government corruption.

The letters said the prosecutors obtained court authorization to renew the wiretaps after an initial 30-day period.

The wiretaps and room bugs are believed to have provided prosecutors with much of the evidence they collected. Sources have said that FBI agents first learned of alleged hush money payments to Johnson through wiretapping Clyburn's phone.

Johnson, who testified before the grand jury last week, has told prosecutors she received about $20,000 in exchange for her refusal to testify four years ago before a federal grand jury investigating alleged cocaine use by Barry and others.

Though defense attorneys characterized the letters as a "housekeeping" measure, the letters created a behind-the-scenes stir at the city's management training retreat in Loudoun County last weekend.

The law gives prosecutors 90 days after terminating an electronic surveillance to notify targets of the surveillance along with anyone whose conversations were overheard, if they can be identified. In this case, the prosecutors apparently obtained court-ordered extensions of the deadline, which is not unusual in ongoing investigations.