A report by the state's Health Policy Commission finds allowing Partners HealthCare to merge with Hallmark Health Systems would increase health care costs on the North Shore.
The commission also has concerns about Partners' acquisition of South Shore Hospital. The commission cannot block the merger but is passing along its concerns to Attorney General Martha Coakley, who is defending the deal.
Partners' competitors oppose the merger.
More from the Associated Press:
The Health Policy Commission found Wednesday that Partners HealthCare's proposed takeover of Hallmark Health System, which runs two community hospitals north of Boston, would reinforce Partners' market power, raise spending on medical care by up to $23 million per year, and increase premiums for employers and consumers.
The Boston Globe reports that the panel asked Partners and Hallmark to submit more information.