RUSSIA’S Syria peace negotiator claimed yesterday that Moscow could prove last month’s alleged chemical weapons attack was a false-flag operation.

“Russia has all the irrefutable evidence that this is a pure provocation on the part of individuals and structures that are not interested in achieving peace on Syrian soil,” Alexander Lavrentyev said, without elaborating.

France has previously claimed it has proof of the Syrian government’s guily. Neither country has revealed its evidence.

Mr Lavrentyev was in Kazakhstan for the latest peace round of preliminary peace talks there. US President Donald Trump ordered a barrage of cruise missiles launched against Syria’s Shayrat air base — key to the fight against Isis — last month in what he claimed was retaliation for the attack on Khan Sheikhoun.

The Organisation for the Prohibition of Chemical Weapons (OPCW) said yesterday it had finally launched a probe into the attack — at its offices in the Netherlands.

“They have some staff, up to 15 I guess, who have started working in our premises here,” said OPCW director-general Ahmet Uzumcu.

Mr Uzumcu was insurgent ally Turkey’s consul in the Syrian city of Aleppo, ambassador to Israel and permanent representative to Nato before taking up his present role.

On Thursday, Syria, Russia, Iran, Turkey and Western-backed insurgent groups meeting in Astana agreed to establish “deescalation zones” in Syria to bolster the patchy ceasefire.

Mr Lavrentyev said yesterday that aircraft of the US-led bombing coalition would be excluded from those zones, and from now on may only attack Isis in eastern Syria and Iraq.