The US Defence Department will release a "substantial number" of photos depicting abuse of prisoners by US personnel in Iraq and Afghanistan, the American Civil Liberties Union said.
The photos will be made available by May 28, the union said, citing a letter from the Justice Department to a federal judge in New York.
The photos' release is in response to a Freedom of Information Act lawsuit filed by the group in 2004 and will include images from prisons in Iraq and Afghanistan at locations other than Abu Ghraib, the group said.
"These photographs provide visual proof that prisoner abuse by US personnel was not aberrational but widespread, reaching far beyond the walls of Abu Ghraib," Amrit Singh, staff attorney with the union, said in a statement.
"Their disclosure is critical for helping the public understand the scope and scale of prisoner abuse as well as for holding senior officials accountable for authorising or permitting such abuse."
The Justice Department letter, signed by Acting US Attorney Lev L. Dassin, followed a September 2008 ruling by the US Court of Appeals for the 2nd Circuit requiring disclosure of the photos and the court's subsequent refusal in March 2009 to rehear the case, the ACLU said.
Since the group's request in 2003, the Bush administration had refused to disclose these images, the ACLU said.
The administration claimed that disclosure of such evidence would generate outrage and would violate US obligations toward detainees under the Geneva Conventions, the group said.
A three-judge panel of the appeals court in September 2008 rejected the Bush administration's position, saying there was significant public interest in disclosure of the photographs, the group said.