Cambridge officials will open bids for construction of a new 225-bed Cambridge City Hospital next week amid criticism of the proposed site of the new hospital.

James J. Mahan, chairman of the hospital's trustees, said yesterday that 225 beds would not be adequate for the City's needs. Mahan indicated that the number of hospital beds should have been increased rather than decreased; the present Cambridge City Hospital contains 246 beds. "We hoped for more, but this is all the City gave us," he said.

Mahan's charges echoed those made last spring by Dr. George P. Berry, then dean of the Medical School, which is associated with the hospital.

Councillor Thomas H. D. Mahoney, discharged yesterday that the new hospital will be too small, recalled that the225 bed figure came from a study of the City's health facilities made in 1960 for the City Council.

Theodore A. Austin, director of the hospital, said last night that a declining population was responsible for the study's recommendation. But he pointed out that Medicare will probably increase the number of patients served by the hospital.

At least one floor of the new building will be devoted to research, but Austin said that it could be easily converted for use by patients.

Harvard's relationship to the Cambridge City Hospital is expected to grow closer when the new building is completed. At present members of Harvard's medical and pediatrics services at Boston City Hospital and the Massachusetts General Hospital spend some time at Cambridge City Hospital. Tentative Harvard plans call for an expansion of to includes surgery, gynecology.