Russia has expelled 23 British diplomats in a carefully calibrated retaliatory move against London, which has accused the Kremlin of orchestrating a nerve toxin attack on a former Russian double agent and his daughter in southern England.
"Twenty three diplomatic staff at the British embassy in Moscow are declared persona non grata and to be expelled within a week", a foreign ministry statement said.
Russian Federation also said it was halting the activities of the British Council, Britain's global organisation for cultural relations and educational opportunities, across the country.
A spokesperson of British Foreign and Commonwealth Office said: "In light of Russia's previous behaviour, we anticipated a response of this kind and the National Security Council will meet early next week to consider next steps".
The Russian statement said the government could take further measures if Britain makes any more "unfriendly" moves.
British police said there is no apparent link between the attack on Glushkov and the poisoning of the Skripals, but both have raised alarm in the west at a time when Russian Federation is increasingly assertive on the global stage and facing investigations over alleged interference in the Donald Trump's election as USA president.
A police vehicle is parked at the British Consulate General, in St.Petersburg, Russia, Saturday, March 17, 2018.
The crisis erupted after Sergei Skripal and his daughter Yulia were exposed to a Soviet-designed nerve agent on March 4 in the English city of Salisbury, leaving them in critical condition.
Defiant Russia vows retaliation over U.S. sanctions, United Kingdom spy accusations
Putin spokesman Dmitry Peskov said in a statement Johnson's claim was a "shocking and inexcusable breach of diplomatic propriety". A former double agent, Skripal betrayed dozens of Russian agents to British intelligence before his arrest in Moscow in 2004.
Mr Bristow told reporters afterwards that Britain had only expelled the Russian diplomats after Moscow had failed to explain how the nerve toxin had got to Salisbury.
Speaking on Russia-24 television, Zakharova said Britain's angry reaction is connected to the war in Syria.
On Thursday, the US joined the U.K., France and Germany in condemning the attack as "an assault on U.K. sovereignty", saying it constituted a breach of worldwide law and calling on Russian Federation to explain its role in the poisoning in Salisbury, England.
March 13 Russian Federation says it won't respond to Britain's deadline unless it is given samples of the nerve agent.
The British government said it was expecting the retaliatory expulsions from Russian Federation.
"We will never tolerate a threat to the life of British citizens and others on British soil from the Russian government", she said, prompting applause.
On Friday, the U.K.'s foreign minister, Boris Johnson, blamed Russian President Vladimir Putin personally for the attack, telling an audience, "We think it overwhelmingly likely that it was his decision to direct the use of a nerve agent on the streets of the United Kingdom, on the streets of Europe, for the first time since the second World War".
Vladimir Dzhabarov, first deputy of the foreign affairs committee in Russia's upper house of parliament, told Moscow-based Interfax news agency that the British Council was used as a cover organization for British intelligence officers.