For the first time in years, officials of the Prince George's County Board of Education and the county NAACP met yesterday in an effort to resolve differences over an acrimonious, 13-year-old desegregation lawsuit.

Afterward, both sides said they are seeking areas of mutual agreement that could be presented to the federal judge overseeing the case. But they added that no resolution had been reached at the meeting and that the suit will proceed.

"I see it as a breakthrough in perhaps coming to a friendly settlement," said School Board Chairman Angelo Castelli. "In the seven years I've been on this board there's never been a meeting of this type . . . . I'm extremely optimistic."

Statements by representatives of the NAACP also were generally positive. "It's just a shame that it has taken all that money and legal effort to come to the point where some honest dialogue can take place," said John Rosser, one of the plaintiffs in the suit.

The optimism expressed by participants was in contrast to what has been a generally adversarial relationship and comes only a week after the school board was criticized by County Executive Parris Glendening for years of intransigence on the issue.

The county has been under court order since 1973 to improve the racial balance of its schools; the suit was filed by the NAACP in 1972.

Yesterday's meeting was scheduled at the request of several black leaders, who also attended. They said they asked school and NAACP officials to come up with a compromise plan using elements of several proposals made to end the legal case. They also urged that more black administrators and teachers be hired and that the officials request a delay in the court proceedings to allow more time for community groups to comment on any plan offered to the court.

Attorneys for the two sides, however, agreed later in the day that they would adhere to the existing court schedule, said school spokesman Brian J. Porter. He said other recommendations made at the meeting will be studied.

The legal timetable requires the school board to submit a desegregation plan by May 13. That plan is expected to be Superintendent John A. Murphy's proposed system of magnet schools , which has been suggested as an alternative to the recommendations of a court-appointed expert panel that called for extensive busing and school closings.

"Whatever plan moves forward . . . should be first communicated to the community as a whole," said Bennie L. Thayer, chairman of the Maryland Rainbow Coalition and one of those requesting yesterday's meeting. "We believe an ideal plan will be eclectic."

In line with the request that more blacks be hired, Thayer raised his concern about a memo written in March by a school official suggesting that the magnet schools be placed in "salable" neighborhoods and administered in ways that would entice "Bowie-type" parents to enroll their children in schools in black neighborhoods.

"As a black leader, I interpreted that letter in a racial tone . . . ," Thayer said. "It was indicative of administrators who now run that system."

Porter said the memo, written by Jane Hammill, coordinator of the county's program for talented and gifted students, has been "widely misinterpreted" and was not intended to be prejudicial. Murphy rejected the suggestions in the memo, according to Porter. Hammill could not be reached for comment, but she issued a statement indicating that she agreed with Murphy's decision.