Sixty-five detainees are being released from Afghanistan's Bagram detention centre despite strong protests by the US, the BBC understands.
Washington argues the move is dangerous, saying it has evidence the men were responsible for carrying out attacks on Nato and Afghan troops.
But Kabul insists there is not enough evidence against the detainees.
Hundreds of prisoners at Bagram jail have been freed since it was put under Afghan control in March last year.
The release on Thursday morning marks a new low in relations between Afghanistan and the US forces in the country, the BBC's David Loyn in Kabul reports.
The Americans believe the move violates the Bagram transfer agreement, our correspondent adds.
This comes as US-led international troops prepare to withdraw fully from the country.
The facility, which housed mainly Taliban and other insurgents captured by Western military forces, has also been at the centre of a number of prisoner abuse allegations.