Russian envoy to UK pens letter to cop sick from nerve agent

The Russian ambassador to Britain has written to a policeman exposed to a nerve agent during the poisoning of a former Russian spy in southwest England, insisting on Moscow's innocence and thanking him for his bravery.

Alexander Yakovenko yesterday told Detective Sergeant Nick Bailey, who was released from hospital on Thursday following two weeks of treatment, that he hoped the officer, as well as targeted ex-Russian spy Sergei Skripal and his daughter, "get well soon".

"I would like to express my sincere gratitude to you for your bravery when reacting to the assault on two Russian nationals," he wrote.

"Please be assured that Russia has nothing to do with this reckless incident and is ready to cooperate with the British authorities," Yakovenko added.

Skripal and daughter Yulia were found poisoned in the southwest English city Salisbury with what Britain has determined was a military grade nerve agent.

Prime Minister Theresa May has blamed Russia for an "attempted assassination".

She won the backing of other European Union leaders at a summit this week, who unanimously agreed it was "highly likely" that Moscow was responsible for the attack.

Russia has ridiculed the accusation, and in an escalating war of words following tit-for-tat diplomatic expulsions, suggested British military laboratory Porton Down may be the source for the attack.

Gary Aitkenhead, the chief executive of the facility, said on Friday there was "no way" a nerve agent could have left the site.

"It's very frustrating to hear that because everyone here knows that's just not true," he told the BBC. "We've got the highest levels of controls."