The Islamic State group has used chemical weapons and is capable of making smaller amounts of chlorine and mustard gas for ammunitions, CIA Director John Brennan said, in a CBS News interview slated to be aired Sunday. Brennan added that the extremist group, also known as ISIS, could potentially seek to export the weapons to the West for financial gains.

"We have a number of instances where ISIL [ISIS] has used chemical munitions on the battlefield," Brennan told CBS News Thursday for the network’s "60 Minutes" news program. "There are reports that ISIS has access to chemical precursors and munitions that they can use," Brennan said.

He also did not rule out the possibility of the export of weapons to the West. "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," Brenna told the news network, which released excerpts of the interview.

The 60-year-old director said the U.S. intelligence is “actively involved” in international effort to destroy the Sunni militant group and “to get as much insight into what they have on the ground inside of Syria and Iraq.”

On Tuesday, U.S. intelligence chief James Clapper said that ISIS fighters have used toxic chemicals in Iraq and Syria, including the blister-causing sulfur mustard, Agence France-Presse reported. Clapper noted that it was the first time an extremist group had made and used a chemical warfare agent in an attack since a 1995 sarin gas attack in a Tokyo subway.

Last September, a U.S. official told BBC that Washington has identified several instances where ISIS fighters have used blister-causing mustard agents. "They're using mustard. We know they are," the official said. "We've seen them use it on at least four separate occasions on both sides of the border — both Iraq and Syria."

The U.S. believes that the group has a cell dedicated to build such weapons, which are used in powder form and packed into traditional explosives like mortar rounds, the official told the British news network. After the weapons explode, the mustard-laced dust causes blisters on those who are exposed to it.