A federal judge agreed today to bar the Prince George's County Board of Education from disposing of at least 14 schools closed last spring, saying the schools might be needed "to preserve flexibility" if a new desegregation plan is ordered by his court.

U.S. District Judge Frank Kaufman gave lawyers for the county and the National Association for the Advancement of Colored People, representing the plaintiffs in the case, one week to draft an order for his signature covering 14 of the 22 schools closed by the board last March because of declining enrollment.

The NAACP lawyers had sought an injunction covering 21 of the schools but agreed to let the school board continue plans to convert three schools into special education centers and turn a fourth over to the county for use as a library. The lawyers reached no decision on the three remaining schools.

Kaufman stressed that he will consider releasing any school from the ban on a case-by-case basis should the school board show an immediate need to use the buildings for something else.

"I don't see any indication that the county is ready to do anything immediately with any particular school," Kaufman said.

Kaufman also said that, based on evidence submitted so far, he believes the issue of whether Prince George's was responsible for maintaining a segregated school system -- as the NAACP has charged -- should be judged by "the effectiveness, not the purpose of their the school board's actions to reduce segregation in the former dual school system." His statement indicated that the NAACP may not have to prove the school board intentionally created racially imbalanced schools, a potential blow to the school board's case.

Kaufman agreed last month to a request by the county NAACP to reopen its desegregation suit against Prince George's County. In its request, the NAACP cited statistics showing that the numbers of predominantly black and predominantly white schools in the county have changed very little since Kaufman ordered officials to desegregate the system in 1972. The school board has maintained that any changes in racial balance were due to demographic shifts in the county, where the percentage of black students overall has doubled in the last nine years.

Last spring the school board voted to close 44 schools over the next three years, shutting 22 of them this fall. State law requires closed schools to be turned over to the county for sale or conversion to other uses.

The NAACP lawyers, arguing that some of the closed schools might be used again in an effective desegregation plan, sought to prevent any sale of the buildings. However, School Superintendent Edward J. Feeney said the county had more than enough underpopulated schools to meet the needs of any desegregation plan.

Kaufman said yesterday he was anxious to get to the substantive issues in the reopened case and asked the lawyers to speed up a previously agreed three-month fact-finding period before the hearing on the main issue.

"I think this case could almost go to trial on all the issues at this time," Kaufman said. "The public has an interest in this case as well as the parties."

Attorney Alfred Solter, who argued the school board case along with school board lawyer Paul Nussbaum, said he was disappointed with Kaufman's decision to grant an order. "I felt the affidavits we filed were sufficient to show damage to both the school board and the county but he saw it the other way and swept them aside," he said.