Greg Scarlatoiu, executive director of the committee, said that prisoners were known to have been "subjected to torture,induced malnutrition and forced labour," but that it hasproven difficult to assess the exact economic benefits.UN enquiry commission estimated in February that North Korea kept 80,000 to 120,000 political prisoners in four large camps including Number 25, where deliberate starvation was used for control and punishment, and that abuses were also rife in ordinary prisons.