Latest: Moscow won't respond to Theresa May's midnight deadline, says Russian Embassy

Latest: Russia will refuse to meet Theresa May's midnight deadline unless Britain agrees to send Moscow samples of the nerve agent used to poison Sergei Skripal.

Update 6.30pm: Russia will refuse to meet Theresa May's midnight deadline unless Britain agrees to send Moscow samples of the nerve agent used to poison Sergei Skripal.

The country's embassy in the UK fired off a salvo of seven tweets in which it said Britain must comply with the Chemical Weapons Convention for a joint investigation and warned the threat of sanctions would "meet with a response".