There have been allegations of abuse at Bagram

US authorities have released the names of 645 prisoners held at Bagram air base in Afghanistan in response to a freedom of information lawsuit.

The lawsuit filed by the American Civil Liberties Union (ACLU) sought documents related to the detention and treatment of prisoners at the base.

The ACLU said vital details about the prisoners had been withheld.

US officials had previously refused to publish the list. One lawyer said the move was "completely unprecedented".

Melissa Goodman, a lawyer at ACLU, said the publication of the names was "an important step toward transparency and accountability at the secretive Bagram prison".

But she said it was only a first step.

"Full transparency and accountability about Bagram requires disclosing how long these people have been imprisoned, where they are from and whether they were captured far from any battlefield or in other countries far from Afghanistan," she said.

A separate letter released by the US Defense Department on Friday said a "very small number" of prisoners were under 16 years of age, the Associated Press news agency reported.

The list of names is for the 645 people held at Bagram in September 2009, when the lawsuit was filed.

"This is completely unprecedented, we've never had access to the list," Ramzi Kassem, a law professor at City University of New York, told AP.

Mr Kassem represents a Yemeni man, Amin al-Bakri, who was captured in Thailand then sent to Bagram.

In his case, a federal judge in Washington ruled that only those Bagram prisoners captured outside Afghanistan could file suit in the US.

US President Barack Obama's administration is appealing against the decision.

Bagram, north of the Afghan capital, Kabul, has been used by the US-led coalition in Afghanistan since the toppling of the Taliban regime in December 2001.

Last year a number of former detainees told the BBC they had been abused at the base.

US officials denied the charges and insisted that all inmates in the facility were treated humanely.