Russia has ordered the expulsion of 23 British diplomats in Moscow as the diplomatic crisis between the two countries deepens.

The latest move by the Russian foreign ministry is in retaliation for the expulsion of the same number of Russian diplomats in Britain in the past few days. They were ordered to leave in response to a nerve agent attack on a former Russian double agent.

The Russian foreign ministry's expulsions had been anticipated. Britain's ambassador to Moscow, Laurie Bristow, was summoned to the ministry building Saturday for just 10 minutes receiving the names of those who’d to be getting on a flight home. As well as expulsions, Moscow has also added the closure of the British Council Cultural Center in Russia and an end to plans for the reopening of a Consulate in St Petersburg. The expulsion numbers exactly mirror those expelled by the British at the Russian Embassy in London. 

British Prime Minister Theresa May was briefed by police chiefs at the scene of the nerve agent attack on former Russian spy Sergei Skripal and his daughter Yulia, saying the diplomatic expulsions in Moscow change nothing.

"Russia's response doesn't change the facts of the matter," said May. "The attempted assassination of two people on British soil for which there is no alternative conclusion other than that the Russian state was culpable. It is Russia that is in flagrant breach of international law and the Chemical Weapons Convention."

Russian Foreign Minister Sergei Lavrov in Kazakhstan accused the UK of failing to produce real evidence of Russian involvement in the nerve agent attack and misleading the public.

On Monday the EU meets to discuss the deepening crisis between London and Moscow, and many member states in the EU are calling for a heightening of sanctions against Russia.

French President Emmanuel Macron and German Chancellor Angela Merkel said this week they both stood by the UK and were considering next steps.