Russia's FSB security service on Friday announced that the accreditation of six British diplomats had been withdrawn for suspected espionage and for "threatening Russia's security".
"As a measure of reprisals to the multiple unfriendly acts of London, the Russian foreign ministry ... has withdrawn the accreditation of six employees from the political department of the British embassy in Moscow," it said in a statement.
Accusing them of carrying out "subversive activities and intelligence" gathering, the FSB said it had "documentary" proof confirming London's "coordination of an escalation in the international political and military situation".
It said the British foreign ministry's Eastern Europe and Central Asia department was coordinating moves aimed at inflicting a "strategic defeat" on Russia.
Russian foreign ministry spokeswoman Maria Zakharova said her ministry entirely agreed with the FSB's "evaluation of the activities of these so-called British diplomats."
"The British embassy has largely flouted the limits set by the Vienna Convention," she said.
Russia's public Rossia-24 television showed images of the six diplomats and identified them. It aired footage claiming to show them leaving the country.
It said the withdrawal of accreditation of a foreign diplomat automatically leads to expulsion.
There was no official confirmation of the identities of the six for the moment.