Human rights groups and former detainees in US custody welcomed Mr Obama's decision to publish memos detailing harsh interrogation techniques used under the Bush administration.But they condemned the decision not to prosecute CIA agents who use interrogation practices described by many as torture.
Mr Obama said he wanted to turn a page on what he called "a dark and painful chapter", condemning the aggressive techniques - including waterboarding, shackling and stripping - used on terror suspects. But he promised not to legally pursue the perpetrators, a move designed to allow the US to put the episodes in the past.
The decision left some bitter in the Muslim world, where there was widespread anger over abuse of detained terror suspects. It threatens to tarnish somewhat Mr Obama's growing popularity among Arabs and Muslims, who have cheered his promises to close the Guantanamo Bay detention facilities and withdraw US troops from Iraq.
The editor of the Saudi Arabia-based Arab News daily, Khaled Almaeena, said the decision not to prosecute "sends the wrong message".
The Obama administration on Thursday released secret CIA memos detailing interrogation tactics sanctioned under the Bush administration. The memos authorised keeping detainees naked, in painful standing positions and in cold cells for long periods of time. Other techniques included depriving them of solid food and slapping them. Sleep deprivation, prolonged shackling and threats to a detainee's family also were used.
Two former top Bush officials on Friday criticised Mr Obama's decision to release the justice department memos, saying it would create "timidity and fear" among US spies.
Mr Obama's attorney general offered CIA operatives legal help if anyone else takes them to court, although the administration's offer of help did not extend to those outside the CIA who approved the so-called enhanced interrogation methods or any CIA officers who may have gone beyond what was allowed.