A/HRC/23/58 in February. The Orthodox Church and the home of its bishop were looted, and much of the church property destroyed. 133. In Yarmouk (Damascus), armed groups either stole cars and trucks or coerced residents into giving them up. In Aleppo, groups at checkpoints steal from Alawite or Shia civilians. 134. The “Islamist Sharia Commission” in Aleppo and Jabhat Al-Nusra in Yarmouk and in Idlib have attempted to curb such theft, arresting or expelling members of some of the groups involved. 135. Anti-government armed groups and government forces and affiliated militia have committed the war crimes of pillage and destruction of property. D. Illegal weapons 136. As the conflict escalates, the potential for the use of chemical weapons is of deepening concern. Chemical weapons include toxic chemicals, munitions, devices and related equipment as defined in the Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and Their Destruction. The Protocol for the Prohibition of the Use in War of Asphyxiating, Poisonous or Other Gases, and of Bacteriological Methods of Warfare, which the Syrian Arab Republic has ratified, is also applicable. The use of chemical weapons is prohibited in all circumstances under customary international humanitarian law, and is a war crime under the Rome Statute. 137. The Government has in its possession a number of chemical weapons. The dangers extend beyond the use of the weapons by the Government itself to the control of such weapons in the event of either fractured command or of any of the affiliated forces gaining access. 138. Anti-government armed groups could gain access to and use chemical weapons. This includes nerve agents, though there is no compelling evidence that these groups possess such weapons or their requisite delivery systems. 139. Allegations were received concerning the use of chemical weapons by both parties. The majority concern their use by government forces. In four attacks – on Khan Al-Asal (Aleppo), on 19 March; Uteibah ( Damascus) on 19 March; Sheikh Maqsood neighbourhood (Aleppo) on 13 April; and Saraqib (Idlib), on 29 April – there are reasonable grounds to believe that limited quantities of toxic chemicals were used. It has not been possible, on the evidence available, to determine the precise chemical agents used, their delivery systems or the perpetrator. Other incidents also remain under investigation. 140. Conclusive findings – particularly in the absence of a large-scale attack – may be reached only after samples taken directly from victims or the site of the alleged attack have been tested. It is therefore of utmost importance that the panel of experts, led by Professor Sellström and assembled under the mechanism established by the Secretary-General to investigate into the alleged use of chemical and biological or toxin weapons, be granted full access to the Syrian Arab Republic. E. Sieges 141. Siege warfare has entered the arsenal of the parties to the conflict. Government forces and affiliated militia have systematically employed sieges across the country, trapping civilians in their homes by controlling the supply of food, water, medicine and 21