The Organization for the Prohibition of Chemical Weapons announced on Wednesday that chlorine was “likely used as a chemical weapon” in an attack on a Syrian town in February.
In line with its mandate, the OPCW did not say which party was behind the attack on Saraqeb, which lies in rebel-held territory in the province of Idlib.
A fact-finding mission by the OPCW determined that "chlorine was released from cylinders by mechanical impact in the Al Talil neighborhood of Saraqeb" on February 4.
The team's conclusions were based on finding two cylinders "which were determined as previously containing chlorine,” the watchdog said in a statement.
Environmental samples also "demonstrated the unusual presence of chlorine in the local environment," said the organization, based in The Hague.
Eleven people had to be treated for breathing difficulties on February 4 after Syrian regime raids on Saraqeb, the Britain-based Syrian Observatory for Human Rights said at the time.
Mohammad Ghaleb Tannari, a doctor in a nearby town in Idlib province, also told AFP at the time that his hospital had treated 11 people.
"All the cases we received had symptoms consistent with inhaling the toxic chlorine gas, including exhaustion, difficulty breathing, and coughing," he said.
The OPCW said its team had interviewed witnesses, and found that a "number of patients at medical facilities shortly after the incident showed signs and symptoms consistent with exposure to chlorine."
"I strongly condemn the use of toxic chemicals as weapons by anyone, for any reason, and in any circumstances," said OPCW head Ahmet Uzumcu.
"Such acts contradict the unequivocal prohibition against chemical weapons."
An OPCW fact-finding team is also currently awaiting the results of its difficult mission to the Syrian town of Douma, after medics and rescuers said 40 people died in a chlorine and sarin attack on April 7.
The team exhumed bodies as well as gathering over 100 environmental samples which are being analyzed in different OPCW-designated labs.
A joint OPCW-United Nations mechanism for Syria had previously concluded that the Syrian regime has used both sarin nerve agent and chlorine, killing and injuring hundreds of civilians.
The mechanism was disbanded in November following a Russian veto at the UN Security Council, a move which ratcheted up tension between Moscow and Western powers over chemical weapons use in Syria.
The Douma chemical attack in April prompted missile strikes by the United States, France and Britain against chemical weapons facilities in Syria.
