Mayor Marion Barry promised yesterday to improve procedures for notifying Fairfax County officials of internal disturbances and escapes at the city's Lorton prison complex, after meeting with Fairfax County Board Chairman John F. Herrity for more than an hour.

Herrity had complained bitterly that the District purposely kept county officials and Lorton residents in the dark during several recent prison disturbances and last week when a minimum-security prisoner "just walked away" from the facility before being captured two hours later.

Barry and Herrity emerged from their meeting in the mayor's District Building office, saying they had agreed to come up with tighter procedures within three weeks for county officials to get early notification of problems at the prison.

Herrity said that the previous agreement between District and Fairfax officials was "vague," but nonetheless the city had "violated the spirit" of the agreement.

County officials need to be notified promptly so they can get police to the perimeter of the prison to ensure public safety, he said.

The Lorton facility has long been a sore point between the District and Virginia. Virginia officials want the prison closed and the prisoners moved into expanded or new facilities in the city.

Both the D.C. Jail and the Lorton complex face a serious crowding problem, and law enforcement officials predict the situation will only get worse because arrests and convictions are rising.

In the past Barry has strongly opposed building any new prison space other than that already planned. But the mayor backed off this stance at a hearing on Capitol Hill last week under pressure from Sen. Arlen Specter (R-Pa.), chairman of the Senate District appropriations subcommittee.

Barry said he will not be opposed to building new cells if the money for them can be found, preferably federal funds, and some space for expanded facilities might be found in the District itself, Barry said then.

Yesterday, Barry refused to comment on any plans to expand prison space and would not say if his forthcoming budget will include anything on the issue.

Herrity said in an interview after a press briefing that the mayor had "indirectly" acknowledged during the meeting that more prison space is needed but that he did not promise that the extra space would not be at Lorton.

"His position of saying 'Never' has been ameliorated somewhat," Herrity said. "I think we are working in that direction."

Herrity also said he had received a letter from the chairman of the Prince William County Board asking to be included in future meetings about Lorton and that interest in the future of the prison is spreading.

The inmate who escaped from Lorton last week was found in Prince William County.