(Reuters) - The Federal Trade Commission on Tuesday sued to prevent Idaho's largest hospital operator from acquiring the state's largest physician group. The agency and the state's attorney general filed the antitrust complaint under seal in federal district court in Idaho, seeking to block St. Luke's Health System's acquisition of the multi-specialty physician practice group, Saltzer Medical Group. St. Luke's, based in Boise, is the state's largest healthcare provider, with six hospitals and more than 10,000 employees. Saltzer, with 44 physicians, specializes in family practice, internal medicine and pediatrics, according to the FTC. "The combination of St. Luke's and Saltzer would give it the market power to demand higher rates for health care services provided by primary care physicians in Nampa, Idaho and surrounding areas, ultimately leading to higher costs for health care consumers," the FTC said in a statement.