The Veterans Affairs Department's medical center in Dayton, Ohio, is investigating alleged improper conduct by one of its doctors, according to the hospital.
Anonymous tips allege a doctor drew blood from patients under anesthesia without their consent, according to the Dayton Daily News.
Sen. Sherrod Brown, D-Ohio, said in a statement he has requested VA complete a "full, fair and prompt investigation."
Rep. Mike Turner, R-Ohio, said in a statement the allegations, if true, are troubling. "The new director, Glen Costie, has indicated that he will take this matter seriously and provide a full accounting to our community," he said.
Costie was named director of the facility in December 2011 after an investigation by the VA inspector general found that a dentist there did not wear clean gloves or sterilize equipment between dental procedures.
A review board set up by VA to investigate the matter said that patients treated by the dentist should be tested for blood-borne illnesses such as hepatitis. Nine patients tested positive for hepatitis B or C, although the review board could not confirm a definitive link between the patients and the dentist.
Following the allegations against the dentist, VA removed former director Guy Richardson in December 2010 and transferred him to a job at the Veterans Integrated Services Network office in Cincinnati.