James Graybeal, a spokesman for the International Security Assistance Force, did not list the facilities involved, The Guardian reported Friday. He also did not say if they were the ones singled out in a United Nations report expected to be released soon.
"Based on concerns over detainee treatment at certain Afghan detention facilities, ISAF suspended the transfer of detainees to these facilities," Graybeal said.
NATO previously halted transfers after a 2011 U.N. report that said guards tore out inmates' toenails and twisted their genitals. The transfers resumed after a period of training and inspection.
But another inmate report is expected to say many earlier practices are still being used. It was scheduled for release last year but has been delayed.
British forces stopped handing prisoners over to the Afghans last year. Some of the U.N. findings became public during a legal challenge to that decision with the release of an email that said there were still problems in jails run by the National Directorate of Security and the Afghan National Police, although mistreatment appears less common.