A UN commission on Syria on Tuesday opened an investigation into alleged chlorine attacks in Idlib and Eastern Ghouta.
Paulo Pinheiro, chair of the Independent International Commission of Inquiry on Syria, said they have received multiple reports that bombs containing chlorine have been used in the town of Saraqeb in Idlib and in Douma in Eastern Ghouta.
He added that the commission is investigating these reports.
Expressing deep concern over the further escalation of violence in Idlib governorate and in Eastern Ghouta, Pinheiro said: "Since the beginning of the year, the increase in violence in Idlib has resulted in another upsurge of internal displacement with over a quarter of a million civilians reportedly fleeing the fighting."
"These reports are extremely troubling, and make a mockery of the so-called de-escalation zones intended to protect civilians from such bombardment," he added.
He said parties to the conflict are violating international humanitarian laws.
"What is happening in Eastern Ghouta is not simply a humanitarian crisis because aid is denied, these sieges involve the international crimes of indiscriminate bombardment and deliberate starvation of the civilian population," Pinheiro said.
UN calls for cease-fire
Also on Tuesday, the UN called for a cease-fire for at least one month in Syria to enable the delivery of humanitarian aid and medical evacuation.
In a joint statement, the UN Resident and Humanitarian Coordinator and UN Representatives said: "The United Nations humanitarian team in Syria warns of the dire consequences of the compounded humanitarian crisis in several parts of the country."
Fran Equiza, a UNICEF representative in Syria, said during a news conference via phone in Geneva: "Children are bearing the brunt of intensifying violence in East Ghouta where they have lived under siege since 2013. Approximately 120 children are in need of urgent medical evacuation."
Home to roughly 400,000 residents, Eastern Ghouta, a suburb of Damascus, has remained under a crippling regime siege for the last five years.
Over the past eight months, the Assad regime has stepped up its siege on Eastern Ghouta, preventing the delivery of food or medicine into the district and leaving hundreds of medical patients in need of treatment.
In the last 30 days, the regime forces have reportedly launched chemical attacks in Eastern Ghouta thrice.
Notably, Eastern Ghouta falls within a network of de-escalation zones — endorsed by Turkey, Russia and Iran — in which acts of aggression are expressly forbidden.
Syria has been locked in a devastating civil war since March 2011, when the Assad regime cracked down on pro-democracy protests with unexpected ferocity.