Samples taken from the chemical weapons attack in Syria last week tested positive for the nerve agent sarin, the British delegation at the world's chemical weapons watchdog said on Thursday.
"UK scientists have analysed samples taken from Khan Shaykhun. These have tested positive for the nerve agent sarin, or a sarin-like substance," the delegation said during a special session at the Organisation for the Prohibition of Chemical Weapons (OPCW) in The Hague.
The UK result confirmed earlier testing by Turkish authorities that concluded that sarin had been used for the first time on a large scale in Syria's civil war since 2013.
The OPCW in The Hague has sent global chemical weapons investigators to Turkey as part of a fact-finding mission to gather biometric samples and interview survivors, sources told Reuters.
The mission will determine whether chemical weapons were used, but is not mandated to assign blame. Its findings, expected in 3 to 4 weeks, will be passed to a joint United Nations-OPCW investigation tasked with identifying individuals or institutions responsible for using chemical weapons.
The chemical attack in Syria killed more than 80 people and wounded at least 550 others on April 4.
The United States responded to the gas attack by firing 59 cruise missiles at a Syrian regime air base. Washington warned Moscow, and Russian troops at the base were not hit.
Moscow has stood by Syrian regime leader Bashar al Assad, saying the poison gas belonged to rebels, an explanation Washington dismisses as beyond credible.
A joint investigation by the OPCW and the United Nations last year had also established that Syrian regime leader Bashar al Assad's forces carried out at least two chemical attacks and that DAESH had used mustard gas as a weapon in the conflict that has ravaged Syria since 2011.