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
Marks and Spencer will become the first UK retailer to add vitamin D to its entire packaged bread range.
An over-the-top 80's action movie parody featuring kung fu Hitler and a David Hasselhoff soundtrack gets almost four million views online.
The government is treating the fight against obesity as a priority, as a new report cautions that one in five cancer deaths is caused by it.