The pro-opposition Syrian Observatory for Human Rights on Tuesday accused a rebel battalion of torturing civilians and extorting money from them in Syria's Northern city of Aleppo.
Torture, kidnapping and summary killings have become a daily aspect of opposition rebels.
But the Observatory, a British-based group with a network of activists across Syria, said it felt compelled to single out the Badr Martyrs' Battalion, a unit of the Free Men of Syria Brigade (Ahrar Suriya), after collecting a large number of witness accounts pointing to frequent detentions and torture.
Rami Abdelrahman, head of the Observatory, emailed Reuters pictures of a man who he said had been tortured by the group. The man's legs had the skin torn open in several places. His back was covered in open lash marks.
The man told the Observatory he had sustained the injuries while being detained for three days.