WASHINGTON: Central Intelligence Agency (CIA) director John Brennan has said that militant Islamic State (IS) group’s fighters have used chemical weapons and have the capability to make small quantities of chlorine and mustard gas, CBS News reported Thursday.

“We have a number of instances where ISIL has used chemical munitions on the battlefield,” Brennan told CBS News, which released excerpts of an interview to air in full on the “60 Minutes” news program on Sunday.

The network added that he told “60 Minutes” the CIA believes that IS has the ability to make small amounts of mustard or chlorine gas for weapons.

“There are reports that ISIS has access to chemical precursors and munitions that they can use,” Brennan said.

Brennan also warned of the possibility that IS could seek to export the weapons to the West for financial gain.

“I think there’s always the potential for that. This is why it’s so important to cut off the various transportation routes and smuggling routes that they have used,” he said.

When asked if there were “American assets on the ground” searching for possible chemical weapons caches or labs, Brennan replied: “United States (US) intelligence is actively involved in being a part of the efforts to destroy ISIL and to get as much insight into what they have on the ground inside of Syria and Iraq.”