The US State Department says Washington believes Daesh terrorists carried out chemical attacks in Syria and Iraq.

Spokesman Mark Toner made the announcement after the Organization for the Prohibition of Chemical Weapons (OPCW) confirmed that Syrians were exposed to sulfur mustard north of Aleppo last August.

�We believe that the Islamic State for Iraq and the Levant, ISIL, or Daesh, was responsible for a sulfur mustard attack in Marea in August 21st, 2015, largely based on photographic evidence as well as Syrian opposition's description of the event. We also believe, based on the available information, that Daesh, or ISIL, was likely responsible for some of the alleged attacks using sulfur mustard in Iraq," said Toner.

The OPCW also said 35 Iraqi Kurdish fighters were sickened by sulfur mustard on the battlefield back then.

A confidential October 29 report by the OPCW concluded that at least two Syrians were exposed to sulfur mustard in Marea, north of Aleppo.

The gas use violates United Nations Security Council resolutions and the 1997 Chemical Weapons Convention.

Sulfur mustard is a Class 1 chemical agent, which means it has very few uses outside chemical warfare.

Used with lethal effectiveness in World War One, it causes severe delayed burns to the eyes, skin and respiratory tract.

By Press TV