The international body charged with establishing who is responsible for chemical attacks in Syria has identified seven potential sites to investigate beginning next month.
Virginia Gamba, who heads the Joint Investigative Mechanism of the United Nations and the Organization for the Prohibition of Chemical Weapons, said in a report to the Security Council on February 22 that it had identified five cases where chemical weapons might have been used.
All of those cases were in Idlib Province in 2014 and 2015.
Two other cases are under investigation in Hama governorate and Marea in Aleppo Province, where Islamic State fighters allegedly used mustard gas in August last year.
Gamba said investigators hope to finalize the list of potential cases by March 1, at which point they would begin in-depth investigations.
Syria's government denies using chemical weapons, but Western states say it is to blame, especially for dropping barrel bombs containing chlorine and other toxic agents by helicopter. The opposition doesn't have such aircraft.
Reports also have surfaced in recent months that the Islamic State extremist group has used toxic chemicals.