The UN chemical weapons watchdog Friday confirmed with "utmost confidence" that mustard gas was used in Syria in August during fighting between rebels and jihadists and "likely" killed a child.
Experts from the Organisation for the Prohibition of Chemical Weapons also found toxic chemicals, including chlorine, were likely used "as a weapon" in an attack in Idlib province in March, the OPCW said in statement.
Three reports have been sent by the head of the OPCW to the body's 192 members after separate missions to investigate incidents in Syria.
In one attack in the town of Marea in Aleppo province on August 21, the OPCW team investigated after "a non-state actor had allegedly used a chemical weapon."
They collected samples and "interviewed two individuals affected by exposure" as well as the doctors that treated them.
"In this case, the team was able to confirm with utmost confidence that at least two people were exposed to sulphur mustard, and that it is very likely that the effects of this chemical weapon resulted in the death of an infant," the OPCW statement said.
Experts also probed allegations that toxic chemicals were unleashed in March in northwestern Idlib.
The team "concluded that the alleged incidents likely involved the use of one or more toxic chemicals - including chlorine - as a weapon."
However, in the third incident in which the Syrian government said its soldiers had been exposed to toxic chemicals in Jobar on the eastern edge of Damascus on August 29, the OPCW "could not confidently determine that a chemical was used as a weapon."