"When you have a nerve agent or whatever, you check it against certain samples that you retain in your laboratories. And Porton Down, as we now all know, is the largest military facility in the United Kingdom that has been dealing with chemical weapons research. And it's actually only eight miles from Salisbury," Russian Envoy to the EU Vladimir Chizhov said when asked how the nerve agent came to be used in Salisbury.
But when the BBC’s Andrew Marr asked him whether he was inferring that Porton Down was "responsible" for the nerve agent in the poisoning attack, Chizhov said, "I don't know. I don't have any evidence of anything having been used."
Russia's ambassador in London, Alexander Yakovenko, asked for "cooler heads." He said that the dispute is "escalating dangerously and out of all proportion."
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UK-Russian relations have seriously deteriorated over the Salisbury incident where former Russian intelligence officer Sergei Skripal and his daughter were found unconscious in a shopping center.
Britain and Russia have each expelled 23 diplomats and taken other measures in the escalating tit-for-tat dispute.