Labor unions supporting nurses on strike against Group Health Association said yesterday that unless a contract is agreed upon swiftly they will call on their thousands of workers in the Washington area to withdraw from the health care group.

In a letter to GHA executive director Dr. Edward J. Hinman, the president of the Metropolitan Washington Council of the AFL-CIO, Joslyn Williams, warned that "unless a contract is reached soon, we will have no alternative but to warn our affiliates to terminate all relationships with GHA."

The council comprises 250 unions with some 25,000 members in the Washington area. Although no exact figure was available, Williams said, "scores of labor unions and tens of thousands of union members" are among the 112,000 members of GHA, the largest health maintenance organization in the area.

The council is understood to be studying the legality of suggesting that the unions withhold their monthly payments to GHA and deposit the funds in an escrow account if a new contract is not hammered out soon.

Meanwhile, representatives of the 85 nurses and five physical therapists who have been on strike since Thursday returned to the bargaining table yesterday following a one-day suspension of negotiations.

The strikers, members of the independent Registered Nurses and Physical Therapists Association, are seeking higher wages and increased staffing from GHA.

Williams said he told Hinman that the council regards management's tactics against the nurses as "union-busting." In the letter, Williams wrote: "The council is outraged at the manner in which Group Health Association is behaving towards its registered nurses."

Hinman met with representatives of several local unions earlier this week, then issued a statement saying: "GHA follows prolabor practices and at no time has this association impaired the right of its employes to organize for self-determination."

GHA itself, which was established in 1937, is a "democratically controlled consumer cooperative whose operating principles and structure are inherited directly from the American labor movement," Hinman said.

He also said that GHA had offered to submit the dispute with its nurses to binding arbitration, but the nurses' union "rejected it."

Bernard Demczuk, political organizer for the American Federation of Government Employees, said that in the meeting with Hinman he and representatives of several other union locals "made it clear that we will call on our members to drop out" of GHA, "although we made no direct threats."

Starting May 3, unionized D.C. and federal workers who are enrolled in GHA have an "open season" for a month in which they may opt for a change in health care plans.

"If they haven't come to a settlement by then," Demczuk said yesterday, "we're definitely going to make a big push to get our members to drop out of GHA and join our union health plan."

AFGE represents 70,000 federal government workers in the metropolitan area and another 10,000 District government employes.

Charles Boswell, president of Local 689 of the Amalgamated Transit Union, wrote to Hinman yesterday expressing the local's support for the nurses.