Latest: 'Russia is not guilty' of spy poisoning, says Russian foreign minister Sergei Lavrov

Latest: Russia's ambassador in London Alexander Yakovenko suggested that the British Government was making allegations against Moscow as part of an "anti-Russian campaign" to divert attention from Brexit.

Update - 1.52pm: Russia's ambassador to the UK Alexander Yakovenko quoted foreign minister Sergey Lavrov as saying Britain's "failure to co-operate" on the Skripal case was a "major violation of the chemical weapons convention".

"The situation will rest on the conscience of those who started this reckless gamble," Mr Lavrov added.