Iran’s Foreign Minister Mohammed Javad Zarif.

Iran’s Foreign Minister Mohammed Javad Zarif, pointing to Sunni Islamist militants in Syria fighting against its allies in Damascus, told the Munich Security Conference that the use of chemical weapons can never be condoned.

Damascus, an ally of majority-shi’ite Iran, this week rejected a recent Human Rights Watch report that said its military and allied forces had used chemical weapons during their capture of Aleppo last year. It instead accuses anti-government fighters of using chemical weapons.

“The use of chemical weapons can never be condoned… Unfortunately the terrorist organizations Nusra and Daesh (Islamic State) still possess chemical weapons,” Zarif said.

The United States last month blacklisted 18 senior Syrian officials it said were connected to the country’s weapons of mass destruction program, after an international investigation found Syrian government forces were responsible for chlorine gas attacks against civilians.