It alleges that the illegal prisons are operated by Chechen officials and Russian security forces and are used to obtain information and confessions through beatings and torture, and for extrajudicial executions.
The group says it has sent its report to Dick Marty, who is heading a probe into alleged secret CIA detention centers in member states of the Council of Europe.
The Chechnya Conflict
The aftermath of a December 2002 Chechen resistance attack on the main government building in Grozny (epa)
CHRONOLOGY
The fighting in Chechnya has raged, with short breaks, since 1994. It has brought misery, death, and destruction to the North Caucasus republic and to Russia as a whole. View an annotated timeline of the conflict.