Representatives for about 80 registered nurses and Group Health Association, the area's largest health maintenance organization, reached agreement on a tentative contract early this morning, ending a 30-day strike that interrupted service to GHA's 112,000 members.

The tentative three-year contract, reached after about four hours of bargaining that ended at about 2 a.m., calls for higher wages and more nurses--the two major issues that led to the strike April 1, according to Josh Williams, president of the Metropolitan Washington Council AFL-CIO, who assited the striking nurses.

Williams said the contract provides for a 16.2 percent wage increase in the first year, with wage reopeners in the following two years.

He said the 16.2 percent increase could be raised during arbitration that must be completed before the contract provisions go into effect. Wages for the next two years also be will subject to arbitration.

Williams said GHA agreed to hire 5.5 new nurses and create two additional positions if it doesn't suffer from a significant drop in membership. GHA handles about 2,000 cases a day.

A spokesman for the nurses said he expects a vote on the tentative agreement tomorrow at the union's annual meeting. A spokesman for the union--the independent Registered Nurses and Physical Therapists Association--said its 85 members probably will return to work this morning at GHA headquarters, 2121 Pensylvannia Ave., as well as at GHA's other health centers in Annandale, Marlow Heights, Hyattsville and Rockville.

Talks between GHA managment and nurses began to pick up last night following GHA's suspension yesterday afternoon of two doctors who walked off their jobs in sympathy with the nurses.

The nurses told GHA if it didn't drop the suspensions it would not return to the bargaining table. A spokesman for the nurses said the 60-day suspension of Donald E. Michell had been dropped. Status of a 30-day suspension against Salman Kazmi was not immediately known. Nurses returned to the bargaining table at 10 p.m.

Throughout the strike, the majority of the 105-member Capitol Alliance of Physicans has supported the nurses. The nurses strike committee had operated out of the CAP headquarters and early in the strike 80 percent of CAP's doctors did not report to work in support of the nurses.

The sudden shortage of medical staff forced GHA to postpone routine patient visits and concentrate on more serious cases.

The first-year salary increase would raise the starting salary for nurses to $17,000 a year. The average salary of GHA nurses ranges from about $14,627 to $19,000 a year.

Also included in the agreement, Williams said, is a $500 a year step increase for some nurses and an additional $200-a-year raise for senior nurses. Williams said a joint labor-management committee will be set up to review and make recommedations for future staff increases.

GHA officials could not immediately be reached for comment on the agreement.