Photos purporting to show prisoner abuse in Iraq were published in 2004
The Pentagon is about to release "hundreds" of photographs showing the alleged abuse of prisoners in Iraq and Afghanistan, US officials say.
The alleged abuses by US personnel are said to relate to President George W Bush's time in office.
The photos are being made public in response to a Freedom of Information lawsuit filed by the American Civil Liberties Union (ACLU) five years ago.
The court order had been contested by the Bush administration.
The US defence department said the Pentagon had agreed to release a "substantial" number of previously unseen photographs by May 28.
"I think it will be in the hundreds," added a Pentagon official, who spoke to reporters on condition of anonymity.
The images relate to around 60 criminal investigations of US military personnel suspected of abusing detainees in Iraq and Afghanistan from 2001 to 2006.
The ACLU says the photos show that the much-publicised abuses at Abu Ghraib prison in Iraq amounted to a specific policy.
"These photographs provide visual proof that prisoner abuse by US personnel was not aberrational but widespread, reaching far beyond the walls of Abu Ghraib," said ACLU lawyer Amrit Singh.
But a Pentagon spokesman downplayed allegations of widespread abuse, saying it had acted swiftly to discipline some 400 personnel found to be involved in abuses.
The release of the photos will increase pressure on the Obama administration to consider prosecuting Bush-era officials for alleged complicity in torture and maltreatment of terrorist suspects, says the BBC's North America Editor Justin Webb.
It follows the publication last week by the Obama administration of four sensitive memos outlining harsh interrogation techniques approved for use by the CIA by the Bush government.
Rights groups have called for CIA personnel involved in any torture cases to be prosecuted, while critics say the move would endanger national security.