A disagreement is developing about Capital Region Baseball's ability to use RFK Stadium on an interim basis if it is awarded a National League expansion franchise that it would like ultimately to locate at a new facility in Northern Virginia.

D.C. Mayor Marion Barry, who also is chairman of the D.C. Armory Board, faxed a letter to NL President Bill White on Wednesday that says Capital Region Baseball, led by Northern Virginia developer Mark Tracz, has no agreement for the use of RFK Stadium if it is awarded one of the two teams the NL will add in 1993. And Armory Board General Manager Jim Dalrymple said yesterday the group "potentially could have problems" negotiating a lease if it is awarded a team over Metropolitan Washington Baseball, a competing group led by Washington developer John "Chip" Akridge.

Akridge's group, which would like to locate a team at RFK Stadium permanently, has a letter of understanding with the Armory Board for a lease of RFK Stadium if it is awarded a team. Dalrymple said yesterday the lease would be for 45 years, with options for a pair of 15-year renewals. The letter of understanding precludes the Armory Board from negotiating with another prospective ownership group, Dalrymple said.

In his letter to White, copies of which went to NL Vice President-Secretary Phyllis Collins and NL Expansion Committee Chairman Douglas Danforth, Barry wrote that he was responding to a story in The Washington Post on Aug. 22 that reported Tracz had said Dalrymple had given his group written assurances it would be able to use RFK Stadium if it is awarded a franchise.

But Capital Region Baseball Vice President Ira Saul said yesterday Dalrymple had verbally informed the group that the Armory Board would negotiate with it in good faith if it is awarded a team over Akridge's group.

"We presented them {Dalrymple and the Armory Board} with a lengthy lease proposal," Saul said.

What Capital Region Baseball has in writing is Dalrymple's response to that proposal. It is a letter in which Dalrymple informed the group he "would recommend that the Armory Board consider" a lease proposal from the group if it is awarded a team over Akridge's group. Capital Region Baseball included the letter in its response to the NL Expansion Committee's questionnaire.

RFK Stadium is "an essential public facility," Saul said. "If they have the potential for a tenant, they're going to allow it to stay vacant?"

Tracz said the group covered this issue during its presentation to the expansion committee Wednesday in New York. "We did not say we have something we don't have," he said. "We were straightforward. We did not misrepresent our position to anybody."

The District government's position seems clear.

"The D.C. Armory Board and the stadium is backing Metropolitan Washington Baseball's interests at this point," Dalrymple said. The letter of understanding with that group "is the egg basket in which we've placed our eggs. . . . We are interested in a long-term solution to baseball in D.C. at RFK Stadium. Right now all of our energies are being expended toward a Washington group headed by Chip Akridge."