Matthew Rycroft revealed that samples taken from the site have tested positive for sarin
At an emergency meeting of the UN Security Council, Britain’s ambassador Matthew Rycroft revealed that samples taken from the site of a deadly toxic gas attack in Syria and analyzed by British scientists have tested positive for sarin or a sarin-like substance
His remarks came as the Security Council discussed a resolution to demand that Assad allows a full investigation into the atrocity which killed 84 people including at least 20 children.
The Syrian government has denied involvement in the attack and blamed rebel groups.
Are we going to get involved with Syria? No
In a futile effort to dissuade Russia from using its Security Council veto to protect assad, Mr Rycroft warned that Russian President Vladimir Putin is on the "wrong side of history" by siding with the "barbaric" Syrian leader.
The exchanges came as a massive demonstration protecting against Russia’s support for the brutal Assad regime started outside the country’s embassy in Kensington.
Mr Rycroft’s comments came after US President Donald Trump said Mr Putin was backing an "evil person" in Assad, as talks took place in Russia between the countries' chief diplomats.
Mr Rycroft warned that Vladimir Putin is on the "wrong side of history"
But Mr Trump, who ordered missile strikes on a Syrian airfield in response to a chemical weapons attack earlier this month, appeared to rule out deeper US involvement in the conflict.
Mr Trump said: "Are we going to get involved with Syria? No."
Analysis of the samples was carried out by chemical weapons scientists at Porton Down and tested positive for sarin "or a sarin-like substance".
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Mr Trump said Mr Putin was backing an "evil person" in Assad
Mr Rycroft said: "The United Kingdom therefore shares the US assessment that it is highly likely that the regime was responsible for a sarin attack on Khan Sheikhoun on April 4."
The diplomat said the Security Council had been "held to ransom by Russia's shameless support for the Assad regime".
He said: "Time and time again Russia has abused its veto to protect the regime and to defend its use of chemical weapons.
Horrific images depict sickening chemical gas attack in Syria
Tue, April 4, 2017
At least 58 people, including nine children, were killed in an air raid that released "toxic gas" on the rebel-held Syrian town of Khan Sheikhoun
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A child receiving treatment at a field hospital after an alleged chemical attack in Idlib, northen Syria
"And what has Russia got in return for its seven vetoes in six years? Let me tell you.
"Russia's initiative in 2013 to dismantle Syria's chemical weapons has been exposed as a shambles. Russian pride in the Astana process has been turned to humiliation.
"And Russia's credibility and reputation across the world have been poisoned by its toxic association with Assad.
Mr Rycroft said the Security Council had been "held to ransom" over Russia's support
"They have chosen to side with a murderous, barbaric criminal, rather than with their international peers.
"They have chosen the wrong side of history."
But he said it was not too late for Russia to change course and use its influence over the Assad regime to bring the civil war to an end.