Russia is to expel 23 British diplomats in a row over the nerve agent attack on an-ex spy and his daughter in the UK.
The Russian foreign ministry said the UK staff would be expelled from Moscow within a week in response to Britain's decision to expel 23 Russian diplomats.
It also said it would close the British Council in Russia, which promotes cultural ties between the nations, and the British Consulate in St Petersburg.
UK Prime Minister Theresa May said: "We anticipated a response of this kind."
She said that the government will consider its next steps "in the coming days, alongside our allies and partners".
"We will never tolerate a threat to the life of British citizens and others on British soil from the Russian Government," she added.
The British Council, the UK's international organisation for cultural relations and educational opportunities, said it was "profoundly disappointed" at being told to cease operations in Russia.
'Shocking and unforgivable'
The UK ordered Russian diplomats to leave the country over the incident on 4 March which the UK government has blamed on Russia – but which Russia denies.
Russian ex-spy Sergei Skripal, 66, and his daughter Yulia Skripal, 33, remain critically ill in hospital, after they were found unconscious on a bench in Salisbury, Wiltshire.
The UK government says they were poisoned with a nerve agent of a type developed by Russia called Novichok, and PM Theresa May has said she believes Moscow is "culpable".
On Friday, Foreign Secretary Boris Johnson said it was "overwhelmingly likely" that Russian President Vladimir Putin had ordered the nerve agent attack.
Responding, Mr Putin's spokesman Dmitry Peskov said the accusations were "shocking and unforgivable".
The tensions come as presidential elections take place in Russia.
Britain's ambassador to Russia, Laurie Bristow, was summoned to Russia's foreign ministry on Saturday.
Following the meeting, Mr Bristow said the UK had no quarrel with the Russian people and would "always do what is necessary to defend ourselves".
BBC
