"A United Nations inquiry into human rights abuses in Syria has found evidence to suggest that rebel forces may have used chemical weapons, its lead investigator has revealed. Carla Del Ponte, a member of the UN independent commission of inquiry on Syria, said that testimony gathered from casualties and medical staff indicated that the nerve agent sarin gas was used by rebel fighters. "Our investigators have been in neighbouring countries interviewing victims, doctors and field hospitals and, according to their report of last week which I have seen, there are strong, concrete suspicions but not yet incontrovertible proof of the use of sarin gas, from the way the victims were treated," Ms Del Ponte said in an interview with Swiss-Italian television, broadcast on Sunday. "This was used on the part of the opposition, the rebels, not by the government authorities," she added, speaking in Italian ."