NEW YORK (AFP) - A United States judge has ordered the government to release a trove of photos depicting abuse of detainees in Iraq and Afghanistan in the latest twist to a long-running legal battle over the images.

In a ruling issued in New York on Friday, US federal judge Alvin Hellerstein gave the government two months to decide how to respond to his order before the photos could be released.

The case has been brought by the American Civil Liberties Union (ACLU) which argues the release of the photos is necessary for an "ongoing national debate about governmental accountability for the abuse of prisoners".

The US government has opposed the release of the photos on the grounds they could provoke a violent backlash and place US forces and personnel overseas at heightened risk of attack.

Congress passed a law in 2009 known as the Protected National Security Documents Act, which allows for the US secretary of defence to withhold the release of documents that are deemed to endanger US personnel.

However in Friday's ruling, Hellerstein said the US government had provided insufficient justification for attempting to block the release of the photos under the 2009 legislation.

"I found that the certification remained deficient because it was not sufficiently individualised and it did not establish the (defence) secretary's own basis for concluding that disclosure would endanger Americans," Hellerstein wrote.

The exact number and content of the photos in question is unclear.

A government brief filed earlier in the court case said several photos showed "soldiers pointing pistols or rifles at the heads of hooded or handcuffed detainees".

US soldiers were implicated in the torture and sexual humiliation of Iraqi prisoners at Baghdad's Abu Ghraib prison when the US military ran it in 2004, a scandal that first broke when photos showing soldiers abusing detainees were published in US media.

Between 2004 and 2006, 11 soldiers - including Lynndie England, who was seen smiling beside naked prisoners being subjected to sexual abuse - were convicted in court martials.

The ACLU was not immediately available to comment on the court ruling on Saturday.

Pentagon spokesman Lieutenant Colonel Myles Caggins said the Defence Department was "studying the judge's ruling and will make any additional responses through court filings".