Chlorine and ammonia is suspected to have been used during helicopter attacks in two urban areas in the west of Syria.
An investigation by the Telegraph tested samples from two separate gas attacks in the city of Kafr Zita, and one other in the village of Talmenes.
Scientific analysis of samples from the attacks - which all took place this month and injured several women and children - showed evidence of chlorine and ammonia use, the newspaper says.
More top news
Prince William and Kate have announced they are to become 'full-time' Royals as they move their family back to London from Norfolk.
Jobs for Americans, a strengthened military, new trade deals and support for police will shape Donald Trump's four years in government.
Donald Trump pledged to put "America first" as he addressed the nation after being sworn in as the 45th president of the United States.