At least 40 civilians, including children, suffered respiratory problems in "chlorine gas attacks" on two rebel-held villages in northwestern Idlib province, the Syrian Observatory for Human Rights monitor said.The monitor said regime forces dropped barrel bombs filled with chlorine -- a toxic agent that can be considered a chemical weapon -- on Saraqeb and Nairab, causing the deaths.A video posted online by activists which could not be verified by AFP showed paramedics splashing a toddler with water, while other children, some coughing, breathed through gas masks.The Observatory, which relies on a network of sources inside Syria, said a baby had died in Nairab.Activists have accused the Syrian regime of using chlorine on civilian areas in the past.In January, the Organisation for the Prohibition of Chemical Weapons said chlorine gas had been used in attacks on three Syrian villages in 2014.In eastern Syria on Saturday, 16 civilians were killed when regime aircraft pounded the city of Deir Ezzor and a nearby ISIS-held village, the monitor said.