Photos purporting to show prisoner abuse in Iraq were published in 2004
The release of more photos of prisoner abuse by US soldiers is "of no benefit" and may inflame opinion against the US, President Barack Obama has said.
The pictures were not "sensational" and every case of abuse had been dealt with by the military, with action taken where appropriate, he said.
The White House previously said it would not fight a court ruling ordering the release of the pictures.
US civil liberties activists accused Mr Obama of adopting Bush-era policies.
The pictures were due to be released by 28 May, according to the court order.
The order was issued by an appeals court in September 2008, in response to a Freedom of Information Act request by the American Civil Liberties Union (ACLU).
Barack Obama explains why he doesn't want the release of the photos
The US defence department had been preparing to release the images, reportedly taken in Iraq and Afghanistan, and the dispute could now end up before the US Supreme Court.
Speaking outside the White House, Mr Obama said he would not tolerate the abuse of prisoners.
However, he had, he said, directed his legal team to fight the court-ordered release of the photos because he was concerned they might "inflame anti-American opinion and put our troops in greater danger".
The Pentagon had not sought to conceal anything, he added, and appropriate action had been taken against individuals involved in abuses. The president 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.
Jonathan Beale, BBC News, Washington
President Obama has clearly concluded that - in this instance - national security trumps transparency.
There is no doubt that President Obama will have disappointed some of his supporters - and, let us be honest, they are those on the left.
But he will have reassured many more that his prime concern is the nation's security and the lives of US troops.
You don't have to be a political genius to work out where the sympathies of the mainstream lie.
The ACLU said the president's "decision not to release the photographs makes a mockery of President Obama's promise of transparency and accountability".
"It's absolutely essential that these photos be released so the public can examine for itself the torture and abuse that was conducted in its name," ACLU attorney Amrit Singh said.
The human rights group Amnesty International also criticised the president's decision, saying human beings had been "tortured and denied basic rights".
But the switch was welcomed by Senator Lindsey Graham, a Republican, and Senator Joe Lieberman, an independent.
"The fact that the president reconsidered the decision is a strength not a weakness," they said in a joint statement.
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.
US MEDIA REACTIONS TO OBAMA'S DECISION
Slowly but surely, Obama is owning the cover-up of his predecessors' war crimes. But covering up war crimes, refusing to prosecute them, promoting those associated with them, and suppressing evidence of them are themselves violations of Geneva and the UN Convention. So Cheney begins to successfully co-opt his successor.
The photos of abuse at Abu Ghraib did aid our enemies and put the lives of US soldiers at risk. We can assume that another round of photos would have had the same effect. That is, the only salutary effect of such a move would have been to soothe the consciences of American liberals who suspect American troops to be war criminals and desperately want the pictures to prove it... There are elements on the left that would expose the president to political danger, and the troops to mortal danger, only to see the last administration implicated in any kind of abuse. The president should be praised for resisting those elements.
I'm speculating, but the White House and Pentagon must not have cherished the idea of having their new start in Afghanistan undermined by the release of pictures that would further inflame the Muslim world. That's not a defense of the decision. I think it's a bad one. But it's an ominous decision for reasons that go beyond upholding the spirit of FOIA.
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