WASHINGTON (AP) _ A federal appeals court ruled Friday that a board set up by Congress to regulate the safety of the government's nuclear weapons plants cannot meet secretly.

A three-judge panel unanimously rejected arguments by the Defense Nuclear Facilities Safety Board that it was exempt from both the Freedom of Information Act and a law requiring open meetings by government agencies.

''We find nothing to indicate that Congress intended to excuse the Board from complying with FOIA or the (Government in the) Sunshine Act,'' the court said.

The five-member board, appointed by the president subject to Senate confirmation, was set up last year to police the safety of the nuclear weapons plants operated by the Energy Department where serious environmental problems have been uncovered in recent years.

Until the board's creation, the Energy Department had sole responsibility for monitoring the safety of the plants, which are exempt from oversight by the Nuclear Regulatory Commission.

The commission regulates commercial nuclear power plants.

The ruling by a three-judge panel of the U.S. Circuit Court of Appeals for the District of Columbia was made on a lawsuit brought by environmental groups to force the five-member board to hold public meetings and respond to requests for documents.

It reversed an earlier finding by U.S. District Judge John G. Penn that the board was exempt from the information act and the sunshine law.

The five-member board has already held several secret meetings, said Dan Reicher, an attorney for the Natural Resources Defense Counsil.

Reicher said Congress created the board to ''ensure that the long-secret environmental problems in the weapons plants were exposed to public scrutiny.''

''This is the agency that is going to make some very fundamental decisions about whether the nuclear weapons plants, which are shut down all over the country, should be restarted,'' he said.

''The secrecy they were trying to maintain would have done nothing to add to the public's faith in the decisions they made,'' Reicher said.

The ruling against the Bush administration was the first opinion written by Circuit Judge A. Raymond Randolph, recently appointed by President Bush.

Randolph was joined by two conservative appointees of former President Reagan, D.H. Ginsburg and James L. Buckley.

There was no answer at the office of the board.

Its five members are Chairman John Conway, former executive vice president of Consolidated Edison Co.; Andrew Eggenberger, a private nuclear energy consultant; Herbert Kouts, formerly a physicist for the Energy Department's Brookhaven National Laboratory; John Crawford Jr., a former deputy assistant energy secretary, and Edson Case, a former official at the Nuclear Regulatory Commission.