Colombian artist Fernando Botero depicts Abu Ghraib abuse
US President Barack Obama has changed his mind and will now attempt to block the publication of photographs showing the abuse of prisoners by US soldiers.
The US government had previously said it would not fight a court ruling ordering the release of the pictures.
Mr Obama now believes the release of the photos would make the job of US troops in Iraq and Afghanistan more difficult, White House officials said.
The pictures were due to be released by 28 May, according to the court ruling.
The court order was issued by the US Court of Appeals for the Second Circuit in September 2008, in response to a Freedom of Information Act request by the American Civil Liberties Union (ACLU).
The US Department of Defence had been preparing to release the images, but Mr Obama has now directed his White House Counsel, Greg Craig, to raise an objection to their publication.
The dispute could now end up before the US Supreme Court.
White House officials said Mr Obama did not feel comfortable with the release of the photographs because he believed their release would endanger US troops, and because the national security implications of such a release had not been fully presented to the court.
Mr Obama had been advised against publication by Defence Secretary Robert Gates, Centcom commander Gen David Petraeus and the commander of US forces in Iraq, Gen Ray Odierno, a Pentagon official said.
The ACLU said it was "surprised and disappointed" by Mr Obama’s decision, but that it would continue to fight for the photograph’s release.
The BBC’s Richard Lister in Washington says that although President Obama has insisted on the need for open government, it appears that on this issue he has been persuaded that - for now at least - such transparency risks doing more harm than good.