Doctors and nurses working for the US military were complicit in the torture of terror suspects in prisons run by the Pentagon and the CIA, an independent report has found.
The Department of the Defense and the CIA demanded that the healthcare personnel "collaborate in intelligence gathering and security practices in a way that inflicted severe harm on detainees in US custody", according to the report released after a two-year investigation.
Such practices included "designing, participating in, and enabling torture and cruel, inhumane and degrading treatment" of detainees, the report said.
The study was conducted by two dozen military, ethics, medical, public health and legal experts.
Collaboration at US prisons in Afghanistan, Guantanamo and the Central Intelligence Agency secret detention sites began after the September 11, 2001 terror attacks.
Study co-author Gerald Thomson said that, in the name of national security, the military trumped the commitment made by medical personnel to practice their profession in an ethical manner.
"Physicians were transformed into agents of the military and performed acts that were contrary to medical ethics and practice," said Mr Thomson, a professor of medicine emeritus at Columbia University.
"We have a responsibility to make sure this never happens again."
The report was supported by the Institute On Medicine As A Profession and the George Soros-funded Open Society Foundations.
It calls on the US Senate Intelligence Committee to fully investigate medical practices at the detention sites, and also urges medical associations to strengthen ethical standards related to the interrogation and detention of detainees.
The study looked at, among other practices, the force-feeding of Guantanamo Bay's hunger strikers, the CIA agents' use of harsh interrogation methods and the simulated drowning known as waterboarding at secret sites.
"Abuse of detainees and health professional participation in this practice is not behind us as a country," co-author Leonard Rubenstein of Johns Hopkins University said.
Both the CIA and the Pentagon have rejected the report's findings.
The report "contains serious inaccuracies and erroneous conclusions", said CIA public affairs chief Dean Boyd.
"It's important to underscore that the CIA does not have any detainees in its custody and President Obama terminated the Rendition, Detention and Interrogation Programme by executive order in 2009," Mr Boyd said.