Attorneys for the Metro transit authority asked a federal judge in Baltimore today to clear the way for subway construction to start in Southeast Washington on a long-delayed section of the Green Line.

Under Metro's new proposal, subway stations would be built at the Washington Navy Yard, in Anacostia and possibly in Congress Heights. The request by Metro's lawyers, however, was initially rebuffed by U.S. District Judge Norman P. Ramsey, who has barred construction of the Green Line's southeastern branch since March of last year.

"That's just totally unreal," Ramsey replied when the proposal to allow construction of a portion of the contested line was broached by Jerome M. Alper, a Washington lawyer representing the transit authority. "That's just idiocy for me to say, 'Go ahead in D.C.' . . . That makes no sense."

Nevertheless, Ramsey said he would consider Metro's request and would issue a ruling later. He instructed the transit agency to present its arguments by Friday and granted Metro's opponents 10 more days to submit a response.

The Green Line remains largely unbuilt as a result of the court contest, neighborhood controversies and shortages of funds. The court battle over the Metro line centers on a portion of the line designed to extend from the Waterfront station at Fourth and M streets SW through Southeast Washington to Prince George's County.

The fight was precipitated by Metro's decision in 1980 to change the Green Line's proposed route through southern Prince George's to include a terminus near Rosecroft Raceway. The shift was soon challenged in court by Prince George's residents and business operators who preferred Metro's earlier proposal for a terminus near Branch Avenue.

Ramsey eventually ordered the transit authority to halt further construction on the section through Anacostia to Rosecroft. He held that Metro had acted improperly by failing to give District and Prince George's residents adequate notice that a change in the route was being considered when hearings were conducted in 1977.

District officials have objected to Ramsey's ruling, contending the Green Line is designed to serve low-income communities where residents depend heavily on public transportation. Officials have argued that the District has become a hostage in a Prince George's dispute.

The request made today by Metro appeared in line with D.C. officials' aims. The transit authority's proposal would permit construction of Green Line sections in the District, while holding off construction in southern Prince George's until the county dispute is settled.

Frank B. Haskell III, a lawyer representing the group fighting the Rosecroft route, said today that he plans to oppose the transit authority's request, arguing that construction of the revised route through Anacostia "would tend to foreclose the Branch Avenue option."

Metro's lawyers disputed this contention. They said they would argue that further delay in building the Green Line in Southeast is not in the public interest and that construction of the Anacostia section would have no effect on where the line goes in Prince George's.