Kremlin asks UK for evidence on spy attack allegations

The Kremlin said on Monday that London would either have to back up its assertions that Russia was behind the poisoning of a former spy and his daughter in Britain with evidence or apologise "sooner or later."

Earlier, Kremlin said that UK's accusations that Putin ordered the Salisbury nerve agent attack were “shocking and unforgivable”.

Britain had accused Russia of being responsible for the use of a Soviet-era nerve agent called Novichok which was used to poison Sergei Skripal and his daughter Yulia.

Kremlin spokesman Dmitry Peskov told a conference call with reporters that Britain's allegations were "difficult to explain... groundless and slanderous".

Kremlin spokesman Dmitry Peskov had said repeatedly that Moscow would retaliate soon for the expulsion of 23 Russian diplomats by Theresa May.

Speaking to reporters on Friday, Peskov repeated denials that Russia had ordered the attack on Sergei Skripal, a former Russian double agent, and his daughter, Yulia, in Salisbury. 

“Any references to our president is nothing other than shocking and unforgivable from the point of view of diplomatic behaviour,” he said.

President Vladimir Putin on Sunday rubbished claims that Russia poisoned a former spy in Britain, on the eve of international chemical weapons experts heading to Britain to probe the attack.

"It's complete drivel, rubbish, nonsense that somebody in Russia would allow themselves to do such a thing ahead of elections and the World Cup," Putin told supporters after winning a fourth term as president.

"We have destroyed all chemical weapons," he added, rejecting Britain's claim that only Moscow could be behind the nerve agent attack on former double agent Sergei Skripal and his daughter Yulia.

Putin said Russia is "ready to take part in the investigation", although earlier on Sunday British Foreign Secretary Boris Johnson accused the Russians of "smug sarcasm and denial" in response to the accusations.