Washington  - A US senator has proposed establishing a truth commission to investigate former president George W Bush's policies in the war on terrorism that many believe led to abuse.

Senator Patrick Leahy, the chairman of the Judiciary Committee, said Wednesday a commission should be established to examine the wiretapping of communications and how policies led to mistreating prisoners.

"Nothing has done more to damage America's place in the world than the revelation that this nation stretched the law and the bounds of executive power to authorize torture and cruel treatment," Leahy, a Democrat, said at a hearing.

Bush authorized harsh interrogations of captives in the war on terrorism. Many civil rights groups concluded the methods, including waterboarding, amounted to torture. Bush also signed off on a secret wiretapping programme that allowed the government to spy on international communications to and from the United States. (dpa)