Poisonous chlorine gas was used as a weapon on a rebel-held Syrian town earlier this year, tests conducted by an international chemical weapons watchdog show.
Investigators from the Organisation for the Prohibition of Chemical Weapons (OPCW) used laboratory tests to determine Saraqib in Idlib province was targeted by chlorine released from cylinders in an attack in February.
As per standard OPCW policy, Wednesdays latest report on the systemic use of banned munitions in the Syrian civil war did not speculate as to who was behind the attack.
Witnesses on the ground, however, told monitors and journalists the chlorine was dropped by illegal barrel bombs from a helicopter. The only fighting force in Syria known to use low-flying helicopters in bombing raids is President Bashar al Assads government.
The OPCW report used samples from soil, canisters and impact sites to determine chlorine was released from cylinders by mechanical impact in the Al Talil neighborhood of Saraqib.
A total of 11 people were treated for breathing difficulties, vomiting and unconsciousness in the 4 February attack – symptoms consistent with exposure to the toxic gas.
Mr Assad has repeatedly denied his government has any chemical weapons stocks after agreeing to give them up to the OPCW in 2013. The opposition has long accused the regime of holding back some of its supply.
The OPCW has said it believes Mr Assad’s government is responsible for at least three chlorine and sarin weapons attacks that have targeted civilianssince then – claims the president also denies. Rebels were found to have used sulfur mustard once, on a small scale.
The watchdog is due to release its initial findings into the deaths of at least 70 people in a suspected chlorine attack in April in what was then the rebel-held Damascus enclave of Douma.
The incident prompted missile strikes on Syrian government weapons research facilities from the US, UK and France.
The report is expected by the end of May.
News agencies contributed to this report