Prince George's County Board of Education attorney Paul Nussbaum, under fire for his role in controversial negotiations to curtail school busing and other matters, accused his critics last night of a "McCarthy-type inquisition." He said he will resign if a majority of the board thinks he should.

Nussbaum read his 5 1/2 page statement in a sometimes faltering voice to startled and grim-faced board members. It came after months of controversy over Nussbaum's participation in negotiations that resulted in an agreement designed to return many students to their neighborhood schools.

That agreement, initialed March 8 by the board's chairman and the local NAACP head, was never implemented and has stirred bitter debate. Last month the NAACP leader, William R. Martin, was ousted as head of the organization's Prince George's branch.

In Nussbaum's first "report of the attorney" in his 20 years with the board, he said he had to respond to "the apparent vendetta against me."

He and Board Chairman Norman Saunders were criticized for failing to tell board members of the negotiations. Nussbaum said he had urged Saunders to tell the members.

In addition to defending his role in the busing negotiations, he addressed questions about his defense of Saunders in a civil suit in the role of private attorney.

He also said he had represented other, unnamed board members on such matters as "wills, divorces, property settlements and traffic charges against members of their families" and represented a prior board chairman "in a multithousand-dollar suit against him."

Nussbaum's bill to the board for his services - $154,000 last year - have come under board scrutiny, and one board member Angelo I. Castelli has requested an audit.

Nussbaum responded: "Not once were there any pejorative aspersions as to my value as board counsel." He said he welcomes an audit, adding, "I will not permit at this late date in my life and career to become intimidated by the methodology of a McCarthy type inquisition. My conscience is clear, my self respect intact."

Nussbaum said he felt he had made a contribution toward education in the county and declared: "I cannot just quit and walk away."

He then challenged the board to vote on his failure. "If . . . a majority of you have come to the conclusion that my services . . . are no longer desired, then I stand ready to tender my resignation."

Board Chairman Saunders, also under fire for his role in the busing negotiations, apparently thwarted his foes last night by failing to appear at an executive (closed) session where some members were planning to call for his resignation. He later attributed his absence to scheduled appearances at school ceremonies.

Saunders' critics on the board have insisted they want ot bring up the matter of the chairmanship in a closed session. Saunders said last night he will stay away from any such meeting.

Five of Saunders' supporters arged the board last night to keep him as chairman, presenting petitions which they said were signed by 3,000 persons.

Castelli, who had offered a proposal to reorganize the board - an action designed to effect Saunders' ouster - called for deferral and it was not brought up in the open meeting.

In other action, the board voted to hold a workshop on busing from 7 to 11:30 p.m. July 9 at Largo High School. The board decided two weeks ago to hold the workshop after failing to agree on three proposals to alter busing patterns.