The US military has told Al Jazeera that it is negotiating with foreign governments to take non-Afghan prisoners from its controversial prison at the Bagram airbase outside Kabul, the Afghan capital.

Vice-Admiral Robert Harward of the Joint Task Force 435, who is head of detainee operations, said "a very, very small population" of foreigners are held at Bagram.

"We're currently co-ordinating with those governments," he told Al Jazeera.

"We're working to move them [the detainees] back into the legal systems of their countries."

The US has promised to hand over the Bagram facility to Afghan authorities by the end of the year.

Al Jazeera's James Bays, reporting from Kabul, said the Afghans wanted the foreign detainees transferred before they take over.

"The Afghans wouldn't want to take control of these detainees when it came under Afghan control, and that's why America is talking to some of the governments where these prisoners come from to see if they will take these prisoners," he said.

"At the same time, since the beginning of the year, there has been a series of releases of Afghan prisoners, substantially reducing the size of the prison population."

Bays said a US source and an Afghan official had put the number of foreign nationals held at Bagram to about 30 and 60 respectively.

The Bagram prison was established after the US-led invasion of Afghanistan in 2001.

Two inmates were killed while being interrogated in 2002, and other former inmates have claimed they have been abused and tortured.