The UN High Commissioner for Human Rights, Navi Pillay, on Tuesday welcomed the appointment of a US special prosecutor to investigate the alleged torture of terrorism suspects detained after the September 11, 2001, attacks.
Pillay also welcomed the release by Washington of Afghan national Mohammed Jawad from the prison facility in Guantanamo Bay, Cuba. He was captured as a teenager in 2002.
"I warmly welcome this responsible decision by the US government to open a preliminary investigation," Pillay said in a statement.
"I hope there is a swift examination of the various allegations of abuses made by former and current detainees in Guantanamo and other US-run prisons," she said. "If they are verified, the next step will involve accountability for anyone who has violated the law."
President Barack Obama has called for the closure of Guantanamo by the end of the year. More than 200 detainees remain locked up there.
Attorney General Eric Holder on Monday appointed prosecutor John Durham to lead the review of cases of CIA interrogators who allegedly abused the detainees.
The Wall Street Journal reported on Tuesday that Durham was already examining the destruction of 92 videotapes of CIA interrogations, which was part of the investigation launched by former president George W Bush in 2008 when the CIA was accused of torturing terrorism suspects.
Pillay also called for curbing the use of US-run secret detention centres. "Secrecy has been a major part of the problem with this type of detention regime."