Assad argued his government has no chemical weapons after agreeing to have them destroyed in 2013. He also ruled out having used chemicals against own people.
"The Conference condemned … the attacks on Khan Sheikhun yesterday. The use of chemical weapons by anyone, anywhere must stop immediately," the co-chairs said in a statement, as read out by EU foreign policy chief Federica Mogherini.
The co-chairs of the Syria Donors Conference in Brussels stressed the importance of maintaining a sovereign, unitary and territorially integral Syria.
"The international community is committed, today recommits to working together to support a peaceful future for Syria and all Syrians in a sovereign, independent, unitary and territorially integral country where all Syrians will be able to live in peace and security," EU foreign policy chief Federica Mogherini said.
The Russian Defense Ministry said early Wednesday the airstrike near Khan Shaykhun was carried out by Syrian aircraft, which struck a terrorist warehouse that stored chemical weapons slated for delivery to Iraq.
The participants of the Syria Donors Conference in Brussels recognized the "special and important" role and responsibility of Russia, Iran and Turkey in implementation of the ceasefire in Syria.
"More attention was given also to the importance of achieving full compliance with the ceasefire agreed on at the Astana meetings and recognized the special and important role and responsibility that the three guarantors hold when it comes to its full implementation," Mogherini told reporters.