IRBIL, Iraq — Iraq's semi-autonomous Kurdistan Regional Government said on Saturday it has evidence Islamic State used chlorine gas as a chemical weapon against Kurdish peshmerga forces.

The Kurdish region's Security Council said in a statement to Reuters that a laboratory analysis of soil and clothing samples from a January suicide car bombing it said IS conducted in northern Iraq found "the samples contained levels of chlorine that suggested the substance was used in weaponized form."

Chlorine is a banned choking agent whose use as a chemical weapon dates back to World War I. It was not possible to independently verify the allegation.