Three US citizens have been arrested in Kabul for allegedly holding Afghans in a private prison, an Afghan intelligence official has said.
Rights groups accuse US troops of abuse at Afghan jails
The high-ranking official told the AFP news agency that the Americans and four Afghans had been detained in a house in the capital on Monday.
US embassy official Roy Glover said he was aware the US citizens were held.
The arrests come as the US coalition reviews its detention centres after complaints of abuse.
The Afghan official said: "That's true, we have arrested three Americans and four Afghans
who were holding seven Afghan men in their private custody."
He said no further details could be given, citing security reasons.
"The case is under investigation right now," he said.
Mr Glover said: "This is my understanding, that they are American citizens. We are looking at the case right now."
The Nato-led International Security Assistance Force said it was "aware of the event".
US Brigadier General Charles Jacoby has completed a "top-to-bottom" review of the 20 holding facilities in Afghanistan run by the US-led coalition.
The results have not yet been made public.
At least three Afghans are believed to have died in custody.
Human rights group Human Rights Watch has said it has documented "numerous cases of mistreatment of detainees" by US troops in Afghanistan.