Soviet-designed nerve agent Novichok, which the UK has said was used to poison ex-spy Sergei Skripal and his daughter Yulia, is not part of an international ban on chemical weapons, the head of a Russian government agency has said.
Vladimir Uiba, the head of the Federal Medical and Biological agency, said according to the Interfax news agency that Novichok did not fall under the Chemical Weapons Convention that entered force in 1997.
He would not say if Russia inherited any amounts of Novichok from the Soviet Union and whether they were destroyed.
Russian Industry and Trade Minister Denis Manturov said earlier on Wednesday that Russia completed the destruction of its chemical weapons stockpiles last year under the convention.
Britain said it will expel 23 Russian diplomats, sever high-level contacts with Moscow and take other measures in response to the poisonings.