A Justice Department policy board is considering numerous proposals to expand information available to local, state and federal law-enforcement authorities via the FBI national computer system.

The disclosure by FBI Director William H. Webster yesterday prompted the American Civil Liberties Union to warn that the proposals, if enacted, would give officials "a multipurpose surveillance system, tracking system and intelligence system."

The system -- the National Crime Information Center (NCIC) -- is currently available to 62,000 law-enforcement agencies and includes files on missing persons, Canadian fugitives and stolen cars as well as an Interstate Identification Index. Police can use the latter file to determine whether a person stopped for a traffic violation or otherwise under suspicion has been named in an arrest warrant elsewhere.

Last month the Justice Department said it was considering expanding the system to include an "Economic Crime Index" -- a file on persons under investigation for white-collar crimes.

Yesterday, in a letter responding to inquiries by Rep. Don Edwards (D-Calif.), chairman of the subcommittee on civil and constitutional rights, Webster said the policy board might first conduct a "pilot study" of that index -- furnishing the information to 11 field offices of the FBI and certain federal agencies -- to determine the feasibility of adding it to the system.

Webster also disclosed in the letter to Edwards that the policy board was thinking about adding information to the Interstate Identification Index, including the names of parolees, of more than 200,000 fugitives and of persons in the federal witness security program.

In addition, law-enforcement authorities would be given a special warning whenever they were dealing with someone arrested for a firearms offense or a violent crime.

Webster said the board also was considering a proposal to inform probation or parole authorities when police inquire about a person on probation or parole, and board subcommittees were considering proposals to notify "appropriate authorities" when police make inquiries about persons on work release or awaiting sentence.

Further, he said, the board may expand the file on Canadian fugitives to include fugitives from other countries with extradition treaties with the United States.

Jerry Berman, an ACLU lawyer and a member of the NCIC policy board's evaluation committee, said the proposals, if enacted, would "turn a system that was represented to the public as a system for the exchange of public-record arrest information between the states into a multipurpose surveillance system, tracking system, and intelligence system, using sophisticated modern technology but also non-public-record information."

Berman said the proposals raised "significant civil liberties and privacy issues" and never came to the attention of the evaluation committee.

The 30-member policy board is composed of law-enforcement officials as well as Justice Department attorneys and FBI agents.