US army medics have not been involved in the widespread abuse of detainees in Guantanamo Bay, Afghanistan and Iraq, an internal military review has found.
The US military says a small minority of medics have seen abuse
About 1,000 US medical personnel were interviewed for the study, of whom 32 said they had seen prisoner abuse.
The study followed claims in the medical journal The Lancet that some army doctors had aided abusive guards. Rights group Amnesty International said the study - which did not involve the Red Cross or detainees - was flawed.
Of the medical staff surveyed, 32 said they had witnessed what could be considered mistreatment. In 26 cases, they reported it to their superiors.
US army surgeon general Lt Gen Kevin Kiley, who carried out the study, said it showed medical staff generally followed proper rules of conduct.
"We found no evidence of systemic problems in detainee medical care," he told reporters.
"The majority of medical personnel interviewed did not observe any abuse and, with few exceptions, those medical personnel who did observe suspected abuse reported it."
'Deaths by beatings'
The instances included actions by medical workers such as "dropping a stretcher a little too roughly, or withholding pain medication until the very last second", the general said.
He acknowledged some problems in policy and record-keeping but said detainees generally experienced good medical care.
Lt Gen Kiley said he could not verify claims by Professor Steven Miles of the University of Minnesota, published in The Lancet, that army medics had been complicit in abuse.
Prof Miles alleged the US military medical system "failed to protect detainees' human rights, sometimes collaborated with interrogators or abusive guards, and failed to properly report injuries or deaths caused by beatings".
The Pentagon dismissed the claims, saying they painted an inaccurate picture and were not based on first-hand evidence.
Jumana Musa, of Amnesty International, criticised the latest review as too limited in its scope.
It failed to show "the linkages between the policies approved by senior officials and the practices of interrogators", he told AFP news agency.
Army guidelines stress medical professionals' duty of care to prisoners, but do not bar them from helping interrogators by giving details of detainees' mental or physical conditions.
Last month, UN investigators accused the US of stalling over their repeated requests to visit detainees at Guantanamo Bay.
The UN says it has evidence that torture has taken place at the prison, amid reports that 520 inmates have had mental breakdowns.