A former high-ranking Syrian diplomat who defected saying his conscience could not allow him to continue representing the regime has emerged from hiding to give his first interview to Sky News.
Khaled al Ayoubi was President Bashar al Assad's most senior figure in Britain and was at the heart of discussions between Britain and Syria over its use of chemical weapons.
After resigning as the charge d'affaire at the Syrian embassy in July 2012, Mr al Ayoubi said he had been granted protection by the UK's Foreign Office.
Since then he said he received death threats from members of Mr Assad's secret intelligence service and had been forced to live at a secret location.
Speaking exclusively to Sky News he said: "When I decided to step down from my post I received messages from people within the Syrian government. They said if I was seen walking down the street in London I would be killed."
The Foreign Office provided him and his wife and two children with a safe house outside London, he said.
Mr al Ayoubi, an ethnic Kurd who joined the Syrian diplomatic service in 2001, now intends to apply for political asylum in the UK on the grounds he could face persecution if he was to return to his home country.
Mr al Ayoubi revealed how the Foreign Office knew last year of the existence of chemical weapons in Syria and that the regime assured authorities they would not be used against civilians.
He said he believed President Assad was planning a chemical attack last summer but a crucial intervention by the British government may have prevented it.
"During the last two weeks of July 2012 there was information delivered to the British government about the preparation done by the regime to start using chemical weapons against the militants and the opposition surrounding Damascus.
"They called me and they asked me to deliver a message to Syria saying that they had information that they have the intention and the will to use chemical weapons against the people and that this was not acceptable.
"I delivered this message to Syria and they sent me an answer saying these chemical weapons are secured, stored and monitored by Syrian army and for use only in the case of aggression from outside the country.
"I think because there was condemnation by many countries at the time the Syrian government stopped their intention and didn’t launch any chemical attack against the opposition.
"Syria has never used chemical weapons on any country even when it has been threatened. Syria has chemical weapons for one use only - to target and kill its own civilians."
A source in the Foreign Office did not dispute Mr al Ayoubi’s claims but added that if Syria had chemical weapons locked away there was "pretty solid" evidence that they had been used since on civilians since.
He said he and other Syrian activists had been left furious by the refusal by some MPs to vote in favour of British involvement in possible military action on Syria.
"Ed Miliband says there should be a diplomatic solution to the problem. You cannot be diplomatic with Assad. He is worse than Adolf Hitler.
"Hitler didn't use chemical weapons against his own people, he did not bomb his own towns and cities. Hitler is junior compared to Assad.
"But both of them are dictators, both of them are killers. Both of them bring agony and suffering to the people around them.
"The Labour party in particular will find themselves on the wrong side of history. How can they sit back and allow thousands of innocent Syrians to die.
"If there is no punishment, if you don’t stop him now, if he doesn’t see that there are serious consequences for killing people by chemical weapons he will use them again and again, over and over again.
"I believe that in the future the Syrian people will look at the people who fought in the British parliament and say you left us to be killed'".