D.C. Mayor Marion Barry informed Washington Redskins owner Jack Kent Cooke yesterday that they will not be able to conclude an agreement for a new football stadium that would keep the Redskins in the District before Barry's term expires Jan. 2.

But Cooke, whose team's lease at RFK Stadium expires at the end of the current season, and Barry expressed confidence about Cooke being able to work toward an agreement with Mayor-Elect Sharon Pratt Dixon and the incoming Council, which will be chaired by John Wilson.

"I am reasonably certain we will be able to reach an agreement with the new mayor and the new city council, subject to my final decision to locate the new stadium in the District of Columbia," Cooke said in a telephone interview.

In a letter to Cooke, Barry said reaching this conclusion was "truly regrettable, since in my judgment the District has responded positively to each and every concern advanced by you as impending execution of the {memorandum of understanding}. The District's negotiating team has settled all outstanding major issues left on the table."

Barry also said in the letter he was "deeply disappointed" that they were not able to reach an agreement. "You and I have both expressed our commitment to keeping the Washington Redskins in the nation's capital," Barry wrote.

He added that in an effort to respond to Cooke's "contemplated timetable," the District transmitted a revision of an August 1989 proposal on June 11, and on Nov. 16 transmitted a shortened version that had been developed as a result of a staff-level meeting between the sides Nov. 14.

Barry said the city has never received "any definitive verbal reaction to the revised document, let alone any written response whatsoever.

"Over the past three years, there have been innumerable meetings with you and your staff," he wrote. "We have responded to your every inquiry. We have shared the result of our exhaustive analysis. We devised a workable solution to minimize the environmental issues while resolving the parking problem.

"We developed a memorandum of understanding which delineated a project planning schedule. The District of Columbia Armory Board has expended substantial staff and resources over $750,000. Yet to this date we are no closer to constructing a stadium than we were three years ago."

Asked what the hang-up is, Cooke said: "There is no hang-up whatsoever. I haven't made a decision to do it {locate the new stadium} in the District of Columbia or Virginia."

But Cooke also said he "deeply" regetted that he and Barry were unable to reach an agreement, "considering the amount of work Mayor Barry and I put into the negotiations."

Barry and John Akridge, leader of a group seeking a Major League Baseball expansion franchise that would be based at the stadium, signed a conditional lease yesterday. Although the lease would enable Akridge's group to make renovations for the 1994 season that would reduce the stadium's seating capacity by 2,000 to 2,500 seats, Cooke said, "There's no problem vis-a-vis continued use of RFK Stadium."

Dixon, who was traveling yesterday and unavailable to comment, will not decide on a course of action regarding a new stadium until she receives a full briefing on the history of the negotiations between Cooke and Barry, according to spokesman Paul Costello.

On Wednesday, Dixon said she doesn't know where Cooke stands on the project. "All of his dialogue has been with the present mayor, so I don't have a real feel for it," she said. "My thinking is it loses a lot of prestige if it's not in Washington. That's part of the attraction of the Redskins, so I would think there are many reasons he would want to keep it here."

Cooke, who has negotiated with Barry since September 1987, has said he is willing to build a facility with his own money. A source familiar with the negotiations has said it would be located on what is now RFK Stadium's Parking Lot 6 and have 72,000 to 78,000 seats, including 365 skyboxes.

The District has indicated it would issue taxable revenue bonds to finance an estimated $60 million worth of infrastructure improvements, such as road construction and sewer and water lines.

Barry said in a statement in October that these financial arrangements would keep the city from paying for the facility "directly or indirectly."

In mid-October, the source familiar with the negotiations said the talks had become snagged when Cooke raised what was thought to be the previously settled issue of filling in a portion of nearby Kingman Lake, an offshoot of the Anacostia River, in order to accommodate additional parking spaces.

There also was disagreement, the source said, when Cooke requested year-round control of all the parking lots that serve the stadium and the armory and that would serve the new stadium.

But Cooke subsequently "backed off" both requests, the source said.

Barry said it is his "genuine hope" that Cooke and Dixon's administration will be able to conclude an agreement. "Perhaps you and the Redskins will now be more expeditious in your response," Barry wrote.

Staff writer Mary Ann French contributed to this report.