The banned nerve agent sarin and chlorine were used in attacks in northern Syria in March of last year, the global chemical weapons watchdog has said.
It is the latest in a series of reports from the Organisation for the Prohibition of Chemical Weapons confirming the use of toxic agents in the country's civil war.
The OPCW is also investigating a suspected chemical attack on 7 April this year in the Douma enclave near Damascus, which prompted missile strikes by the United States, France and the UK.
It is expected to publish the results of that inquiry later this month.
The OPCW said in a statement that sarin had been used south of the city of Ltamenah in the Hama area on 24 March 2017.
It also "concluded that chlorine was very likely used as a chemical weapon at Ltamenah Hospital and the surrounding area on 25 March 2017".
The findings are based on witness testimony, epidemiological analysis and environmental samples, it said.
The OPCW did not assign blame for the attack. Syria has denied using chemical weapons.
Syrian government forces have used both sarin and chlorine, according to a United Nations-OPCW joint investigation, while rebel forces used sulphur mustard gas once.
Their so-called JIM mission was disbanded in November after a proposed renewal of its mandate was vetoed by Russia at the UN Security Council.