Global human rights campaigner Human Rights Watch has demanded that Syrian opposition leaders \"condemn and forbid\" reported human rights abuses by armed groups. In an open letter it said: \"In the face of evidence of human rights abuses by armed opposition members, Human Rights Watch calls on the leadership of leading opposition groups including the Syrian National Council (SNC) and its Military Bureau to condemn such practices by the armed opposition and to work to prevent such unlawful practices. We recognise that the perpetrators of these abuses are not always easy to identify nor do they necessarily belong to an organised command structure that follows the orders of the SNC or other opposition groups. Some reports received by Human Rights Watch indicate that in addition to armed groups with political motivations, criminal gangs, sometimes operating in the name of the opposition, may be carrying out some of these crimes.\" Much of the evidence compiled by the group is based on video footage, including testimony from rebels themselves. It showd proof of kidnappings, including the case where seven Iranian nationals were abducted of whom reportedly two were civilians. The videos also showed torture where Syrian security forces or their alleged supporters confessed to crimes under circumstances in which it appears that their statements were made under duress. At least 18 of these videos show detainees who are bruised, bleeding, or show other signs of physical abuse. Human Rights Watch said it could not independently confirm the authenticity of these videos. Other video footage reviewed by the group indicated that members of armed opposition groups had executed people in their custody whom they suspected of crimes against the opposition. \"Following the creation of the SNC Military Bureau on 1 March, 2012, to liaise with, unify, and supervise armed opposition groups including the Free Syrian Army, Human Rights Watch calls on the Bureau to condemn and forbid these abuses in order to achieve its objective of ensuring members of the armed opposition comply with international humanitarian law and to meet its human rights obligations,\" said the group in a statement.