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.