The number of U.S. Veterans Affairs facilities being investigated for problems involving delays in treating patients has more than doubled to 26, CNN reported on Tuesday.
The network cited the VA's Office of Inspector General, adding that the inspector general told a Senate committee last week there were 10 facilities under investigation.
VA officials could not be reached for immediate comment.
The allegations that delays in treatment at veterans' hospitals could have led to otherwise preventable deaths has sparked a growing political scandal, including calls for the resignation of VA Secretary Eric Shinseki.
The secretary was grilled at a Senate hearing last week where Democrats joined Republicans to demand stronger action to fix problems after officials at VA medical facilities in Phoenix were accused of covering up long wait times for patients, including 40 who died while awaiting care.
Shinseki told the lawmakers he was "mad as hell" about allegations of schemes to mask waiting times for care at VA facilities, but said the VA would wait for its inspector general to complete its investigation before acting on the Phoenix allegations.
A top department official, undersecretary of health Dr. Robert Petzel, resigned on Friday in a move critics said was an effort at damage control.
The VA has put three senior officials in Phoenix on administrative leave after doctors there said they were ordered to hold veterans' names for months on a secret waiting list until a spot opened up on an official list that met the agency's two-week waiting-time goals.
Allegations have been reported about similar cover-up schemes at VA medical facilities in at least seven other cities. The agency runs the largest U.S. healthcare group, overseeing some 1,700 hospitals, clinics, nursing homes and other facilities.