Russia has called on Britain to prove it did not poison former double agent Sergei Skripal, saying that unless it sees proof it will consider the incident an attempt on the lives of Russian citizens.
Ties between London and Moscow are badly strained by the poisoning of Skripal and his daughter, Yulia, who remain in critical condition after being exposed to a powerful nerve toxin in the southern English city of Salisbury on March 4.
