The NATO-led mission in Afghanistan has suspended the transfer of detainees to several Afghan jails, while allegations of torture are investigated.
The BBC reports that the accusations have been made in unpublished United Nations report which describes how prisoners were beaten and in some cases given electric shocks.
The jails in at least six locations are run by the Afghan police and intelligence service.
A NATO official says the suspension is a prudent measure until the allegations can be investigated.
The UN report says prisoners were beaten with rubber hoses and threatened with sexual assault.
It cited the case of a 19-year-old man who was beaten for 19 days in a row, before eventually bleeding to death.
Most of those held were suspected of being insurgents and some were held without charge.
Last year, Britain's Ministry of Defence agreed to halt the transfer of prisoners to jails in Kabul run by the Afghan intellingence service (NDS) after a court ruled that they faced the risk of torture or serious mistreatment.