The Russian Foreign Ministry announced on Saturday morning that the 23 diplomatic representatives of the British Embassy in Moscow should leave Russia within a week.
Britain's ambassador to Russia says the nerve agent poisoning of a former Russian double agent and his daughter in Britain was an attack on global values.
"We will always do what is necessary to defend ourselves, our allies and our values against an attack of this sort, which is an attack not only on the United Kingdom, but upon the worldwide rules-based system on which all countries, including Russian Federation, depend for their safety and security", Bristow told reporters.
The British consulate in St. Petersburg was also ordered to close and the British Council must stop its work in Russia, the Russian Foreign Ministry said in a website statement Saturday.
Russian Federation on Saturday ordered 23 British diplomats to leave the country within a week, escalating a diplomatic row after a former spy and his daughter were poisoned on British soil. The pair remain in critical condition.
Asked by a Reuters reporter in the Kazakh capital if Moscow would expel British diplomats, Russian Foreign Minister Sergei Lavrov smiled and said on Friday: "We will, of course".
Moscow responds to British measures in dispute over poisoning of former spy.
May announced the expulsion of 23 Russian diplomats who she said were actually intelligence operatives on Wednesday after giving the Kremlin 24 hours to provide an explanation for how a Soviet-made, military-grade nerve agent had been used in the attempted assassination of Sergei Skripal, a former Russia double agent. "If further actions of an unfriendly nature are taken against Russia, the Russian side reserves the right to take other retaliatory measures", the ministry said. Putin's spokesman denounced the claim.