The Washington Post newspaper has reported that the United States has freed "high level" detainees from a military prison in Afghanistan over the past two years in an effort to promote reconciliation with insurgent groups.
Citing U.S. officials on condition of anonymity, the daily said prisoners were only released if they were not considered to be a security threat.
U.S. Embassy spokesman Gavin Sundall confirmed the program but said it was rarely used.
The Post said the unknown number of releases was meant to produce tactical gains and was not part of a wider deal with insurgents.
In exchange, U.S. military chiefs have received assurances from tribal elders that they would reduce violence in their districts.
The releases were subject to approval by the top U.S. commander and military lawyer in Afghanistan.
With reporting by AFP