In a new report, Amnesty said the NATO-led International Security Assistance Force (ISAF) could be exposing detainees to abuse, including whipping, beatings, exposure to extreme cold and food deprivation.
It singled out Afghanistan's National Directorate of Security (NDS) as a major offender and said the agency "currently poses a serious threat to those in its custody".
Amnesty said Britain, Canada, Denmark, the Netherlands and Norway had signed "memorandums of understanding" and other accords on prisoner transfers with the Afghan authorities, and that Belgium, France, Germany and Sweden may do so too.
The agreements, it said, "do not fulfil the absolute and non-derogable legal obligation not to put anyone in a situation where they are at risk of torture or other ill-treatment."
ISAF, which comprises some 40,000 troops from 37 nations, is trying to spread the influence of President Hamid Karzai's weak central government across the strife-torn country, but is battling a tenacious Taliban-led insurgency.
Amnesty urged ISAF to "immediately declare a moratorium on any further transfers of detainees to the Afghan authorities and take responsibility for the custody of such detainees until effective safeguards against torture and other ill-treatment are introduced in the Afghan detention system."
It called on them not to rely on memorandums of understanding as a guarantee that prisoners would not be tortured once they are handed over, and help train prison staff and reform the prison system.
It urged Afghanistan to reform the NDS and allow independent monitors into all detention facilities.
NATO spokesman James Appathurai said the military alliance had no evidence that any prisoners were being abused and did not plan to build its own jails just in case.
"NATO has no proof of ill-treatment or of torture of detainees that its forces have transferred to the Afghans," he said.
"It's true there are concerns. This is precisely why the allies have invested, and a lot, in the reform of the Afghan institutions, including the NDS. It's the only appropriate and acceptable way to improve the situation."
But "Afghanistan is a sovereign country", he said. "It's not up to NATO to put a parallel detention system in place on Afghan territory.
Copyright © AFP 2007