“According to the testimonies we have gathered, the rebels have used chemical weapons, making use of sarin gas,” del Ponte, a former war crimes prosecutor, said in an interview with Swiss radio late on Sunday.
“We still have to deepen our investigation, verify and confirm (the findings) through new witness testimony, but according to what we have established so far, it is at the moment opponents of the regime who are using sarin gas,” she added.
She stressed that the UN commission of inquiry on Syria, which she is a part of, had far from finished its investigation.
Turkish authorities are carrying out blood tests on Syrians who have fled the fighting at home to determine if they have been victims of chemical weapons, a medical source said Monday.
“Samples have been taken from people wounded in Syria who have been transported to Turkey,” the source said on condition of anonymity, adding that the results were not yet known.
Read more: telegraph.co.uk