The Prince George's County Board of Education was told last night that an attempt to oust Norman H. Saunders from the board chairmanship is illegal.

The move to oust Saunders surfaced in June amid criticism of his efforts to negotiate reductions in school busing.

Paul M. Nussbaum, the board's attorney, said last night a resolution sponsored by member Angelo I. Castelli calling for a board reorganization that would remove Saunders from the chairmanship cannot legally be considered.

Nussbaum, who spoke to the board in an executive (closed) session, said he would explain the legal basis for his opinion in writing next week. He would not elaborate to a reporter.

Castelli said after the meeting that he has withdrawn his resolution, adding, "even if I had the five votes [needed to pass the resolution], we couldn't do it."

Some board members said Castelli may be interested in seeking a second opinion on the legality of a reorganization move.

Board member A. James Golato said that even if a way were found to circumvent Nussbaum's opinion, he doubts that any new move to oust Saunders would come before the chairman's one-year term expires in December. Golato said he no longer favors reorganization and doubts that any such move has enough board support to pass.

As in the past, Saunders refused last night to attend the portion of the closed board meeting at which reorganization was discussed.

"To me, reorganization is a moral issue, a matter of my own credibility, and anything about it I want discussed in the open at a regular board meeting," he said.

Criticism of Saunders has centered on his attempt to negotiate an agreement to reduce busing with the county's NAACP head without the knowledge of other board members. The "memorandum of understanding" on busing that was agreed to fell apart when it was repudiated by the NAACP.

At one point this summer, board members privately discussed removing Nussbaum for the role he played in the busing negotiations. They gave him a vote of confidence after he made an impassioned speech defending his actions.