The Justice Department's internal investigative unit handed the Senate's Billy Carter subcommittee a political hot potato yesterday -- its own report on the Libyan connection of the president's brother, complete with a reportedly critical assessment of the parts played by several Carter administration officials, including Attorney General Benjamin R. Civiletti.

The report also is said to criticize the White House for failing to cooperate in the investigation.

Michael E. Shaheen Jr., head of the department's office of professional responsibility, forwarded three copies of what he termed a "status report" to Sen. Birch Bayh (D-Ind.), the subcommittee chairman, Strom Thurmond (R-S.C.) the ranking minority member, and Philip W. Tone, the special counsel. He requested that the report not be released publicly because the investigation was not yet complete.

A department spokesman said Shaheen was sending the interim report because he'd promised something to the committee by the end of this month. Receipt of the Justice report puts the subcommittee in the delicate position of determining how to deal with press requests for it a week before the presidential election.

Shaheen's office opened an investigation when Civiletti disclosed that he had discussed the department's investigation of Billy Carter with the president. The revelation created a furor because Civiletti consistently had denied speaking to the president about the case at all.

Billy Carter registered as a foreign agent for Libya this summer after Justice investigators found that he had accepted $220,000 from Libyan officials. In its report, the subcommittee criticized Civiletti, and some White House officials, but concluded no one broke the law.

A spokesman for subcommittee member Richard Lugar (R-Ind.) said the senator will ask Justice to release the report.

Thurmond also issued a statement calling on Justice to release the report. As one Senate source put it, "They threw this hot potato at us and we're throwing it right back."