The global chemical weapons watchdog has said the nerve agent sarin and toxic chemical chlorine were "very likely" used as weapons in two attacks in central Syria in March 2017.
The Organisation for the Prohibition of Chemical Weapons (OCPW) said its fact-finding mission probing alleged attacks in Syria found that "sarin was very likely used as a chemical weapon in the south of Ltamenah" in Hama province on March 24.
It added that chlorine was very likely used a day later at and near Ltamenah Hospital.
The OPCW's fact-finding team is not mandated to apportion blame for chemical attacks.
The organisation said its findings were based on witness testimony and analysis of samples.
The attack occurred as government forces, backed by planes and helicopters, were battling rebels in the area.
Days after the Latamneh attacks, sarin was used in a deadly attack at nearby Khan Sheikhoun, killing scores of people.
That attack was blamed by the now-defunct joint UN-OPCW investigative team on Syrian government forces. Damascus denies responsibility.
Physicians for Human Rights (PHR) reported the hospital attack last year, saying that the Latamneh surgical hospital - a facility built into a cave to protect it from air strikes - was hit by multiple barrel bombs.
PHR said at the time that the attack only caused minor structural damage, but multiple sources inside the hospital testified that at least one of the bombs contained a chemical agent.
The hospital's coordinator told PHR that the attack and chemical exposure led to the death of one of the hospital's doctors, Dr Ahmed Darwish, the group said.
Doctors Without Borders, also known as MSF, said the hospital in Latamneh was supported by the group.
It said a bomb dropped by a helicopter hit the entrance of the building, and that information collected by the hospital's medical staff suggested that chemical weapons were used.
The OPCW is expected within weeks to announce the result of its investigation into a suspected chemical attack on April 7 on the town of Douma, near the capital.
The US, UK and France blamed Syrian government forces and launched punitive air strikes.
Syria denied responsibility.