"Toxic chemicals, most likely pulmonary irritating agents, such as chlorine have been used in Syria," the Organization for the Prohibition of Chemical Weapons (OPCW) stated on Tuesday, Xinhua reported.
The OPCW/UN chemical weapons inspectors came under attack last month. The incident prevented the fact-finding mission from conducting an important field visit.
Although they had to shorten their work, the inspectors now claim to have found information suggesting that the chemicals had been used in the Syria conflict.
"I commend the commitment and dedication of the team of OPCW and UN officials who courageously pressed on with the task that was assigned to them, despite the well-known risks," said OPCW Director-General Ahmet Uzumcu in the statement.
The director-general added that ongoing delays in transporting the remaining 8 percent of chemicals mean that Syria will miss the target date of June 30 for the complete destruction of its chemical weapons program.
He called on Syrian authorities to redouble their efforts to complete the transportation of the remaining chemicals without further delay.