Russian diplomat sent home at Foreign Office request
A diplomat at the Russian embassy in London has been sent home after the Foreign Office requested the withdrawal earlier this month.
The Foreign Office said it made the request on 10 December.
It said the request was because of "clear evidence of activities by the Russian intelligence services against UK interests".
Russia then made a similar request about a UK diplomat six days later. Both have returned to their homes.
Referring to Russia's request, Foreign Secretary William Hague said the UK "rejects any basis for that action".
Mr Hague said: "We remain open to a more productive relationship with Russia, as with any other country, on the basis of respect for our laws."
There has been no comment from the Russian Embassy in London.
It was hoped that the mutual withdrawal would not sour relations, the BBC's diplomatic correspondent Bridget Kendall says.
It was only recently agreed that the Russian foreign minister would visit London early next year and that, later in 2011, Prime Minister David Cameron would meet President Dmitry Medvedev in Moscow.
A Whitehall source said the Russian diplomat removed was not connected to the ongoing detention of the former parliamentary researcher Katia Zatuliveter.
The 25-year-old Russian is currently appealing against the British deportation order issued on national security grounds.