A federal mediator has ordered hospital administrators and striking nurses in Prince George's County back to the bargaining table next Tuesday in an effort to settle contract disputes that prompted several hundred nurses from three county health facilities to walk out Monday.

Yesterday, both sides insisted in separate press conferences that their positions were firm and accused each other of misinforming the public.

Six chief doctors at Prince George's General Hospital, the county's largest and most affected hospital, stated that "care is adequate" there. "Adequate means that things are good or better," said Dr. George Hajjan, chief of emergency medicine.

Hajjan said the emergency room was seeing the same number of patients this week as it was before the strike. Patients from three of four outpatient clinics that closed because of the strike are being seen in the emergency room, he said.

Several of the emergency-room nurses have continued to work, he said, and there are plenty of nonnursing volunteers to do jobs such as pushing wheelchairs. Nurses from other areas are also volunteering, including two sisters of hospital corporation President Robert J. Brady Jr., according to a hospital spokesman.

Dr. Haluk Boneval, president of the medical staff at Prince George's General, said that the strike has not interfered with the hospital's inspection by the Joint Commission on Accreditation of Hospitals. The three-day inspection is to be completed today.

The nurses' union countered the hospital's statements at a Cheverly home donated by Dr. William Holbrook, a Prince George's General physician. "If the hospital wasn't adequately staffed when we were there, how could it be adequately staffed now?" asked Larry Grosser, chief negotiator for the nurses' union. Grosser estimated that about 500 of the 650 nurses represented by the union and working at the three facilities are supporting the strike.

He labeled as "simply untrue" figures from hospital spokesman Mike Canning that between 30 and 50 percent of the nurses who were scheduled to work have shown up for their shifts since Monday.

Not all of the doctors at the hospital agreed with their colleagues that services have not been affected. Earlier this week, a letter from internists Michael Berard and Mark Parkhurst circulated around the hospital, supporting the nurses and asking fellow physicians to limit their use of inpatient services during the strike.

"It is our opinion that without these people, no matter how much replacement . . . is done, Prince George's Hospital cannot possibly supply the kind of care we expect and depend upon," the letter said.

Dr. Iradj Mahdavi, a pediatrician who has brought buckets of chicken to the picket line at Prince George's hospital, said he is concerned that there are not enough registered nurses working in the intensive care nursery there. Some supervisory nurses who have not tended patients in some time are doing the work, Mahdavi said, but "they aren't with it."

Hospital officials said yesterday that their nurses are earning salaries as high or higher than other nurses in nearby Maryland hospitals whose patient charges are regulated by the state Cost Review Commission.

But union officials countered that that comparison is unfair because those Maryland facilities are small. Grosser passed out a survey yesterday that showed beginning registered nurses' annual salaries at Prince George's General were about $1,000 to $2,000 below those at similar large area hospitals such as D.C. General, Greater Southeast, George Washington University and Holy Cross.