Moscow has announced it is expelling 23 British diplomats in response to Theresa May's decision to expel the same number of Russian diplomats from the United Kingdom following the Salisbury nerve agent attack. It also said in a statement that it is ordering the closure of the British Council, a government-backed organization for cultural and scientific co-operation, and that it is ending an agreement to reopen the British consulate in St. Petersburg.
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.
Russian Foreign Ministry spokeswoman Maria Zakharova said on Friday Moscow had already decided on retaliatory measures, which she said Britain would be informed of in the near future.
"The attempted assassination of two people on British soil, for which there is no alternative conclusion other than that the Russian state was culpable".
"A total of 23 diplomatic employees of the British Embassy in Moscow are declared personae non gratae and must leave within a week", said the statement, warning that Moscow retained the right to respond if Britain continues to take unfriendly steps against Russian Federation.
Russian Federation has complained that Britain has failed to provide any evidence of its involvement in the Salisbury attack and has said it is shocked and bemused by the allegations.
Britain has escalated a war of words with Russian Federation over the incident in recent days.
Britain's foreign secretary accused Russian President Vladimir Putin of personally ordering the poisoning of the Skripals.
Russian Federation to expel 23 United Kingdom diplomats
The tensions threaten to overshadow Putin's expected re-election Sunday for another six-year presidential term. On March 17, 2018, Russian Federation ordered the expulsion of 23 British Diplomats in counter-retaliation.
Speaking at the Conservative spring forum on Saturday, Theresa May said Britain "would never tolerate a threat to the life" of its citizens, or others in the country, from the Russian government.
Western powers see the attack as the latest sign of alleged Russian meddling overseas.
Britain, the US, Germany and France have jointly called on Russia to explain the attack, while US President Donald Trump has said it looks as if the Russians were behind it.
Russian Federation has said is open to cooperation with Britain, but has refused Britain's demands to explain how Novichok, a nerve agent developed by the Soviet military, was used against the Skripals.
It comes after NHS England said Detective Sergeant Nick Bailey, the police officer exposed to the Novichok agent in Salisbury, is no longer in a critical condition.
The announcement is the latest development in an ongoing worldwide saga that began on March 4, when Sergei Skripal, a former Soviet and Russian spy, was found unconscious on a bench next to his daughter, Yulia, in the English city of Salisbury.
British police appealed Saturday for witnesses who can help investigators reconstruct the Skripals' movements in the crucial hours before they were found unconscious.
The measures included the expulsion of 23 diplomats in a week, the freezing of Russian state assets in Britain, the suspension of all planned high-level bilateral contacts and boycotting the ministers and the Royal Family from attending the FIFA World Cup in Russia.