Russia has announced the expulsion of 23 British diplomats amid tensions over the nerve agent attack on a former spy and his daughter in the UK.
The Russian foreign ministry said staff from the UK's Moscow embassy would be expelled within a week.
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.
The move comes in response to Britain's decision to expel 23 Russian diplomats.
They were ordered to leave over the incident on 4 March which the UK government has blamed on Russia - but which Russia denies.
The UK Foreign Office said it had "anticipated a response of this kind" from Russia and the National Security Council would meet early next week to consider its next steps.
Its statement added: "Russia's response doesn't change the facts of the matter - the attempted assassination of two people on British soil, for which there is no alternative conclusion other than that the Russian State was culpable."
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 BBC reports that 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".
