Russia’s Foreign Ministry has expressed regret over the British Foreign Secretary’s decision to expel a Russian diplomat from the UK, and called it an “unfriendly" move.

­In a written statement on Tuesday, William Hague said that on December 10 he asked the Russian embassy in London to withdraw a member of their staff from the UK, following "clear evidence of activities by the Russian intelligence services against UK interests."

Russia’s Foreign Ministry confirmed that a UK official was booted from the British embassy in Moscow on December 16 in response.

 “The British side made an unfriendly move recently by groundlessly declaring one of the staff members at Russia’s embassy in London a persona non grata,” – said the ministry on Wednesday.

 “It is regrettable that the move was made just as the first reassuring tendencies in our relations with Britain were beginning to emerge," the Russian officials said.

Earlier this month, a Russian working as a parliamentary aide to a British MP was arrested in London for allegedly spying.

The last tit-for-tat expulsions between Russia and the UK were in 2007, when three Russian diplomats were expelled from London. The move was in protest at the Kremlin's refusal to extradite Andrey Lugovoy, who was charged by the Crown Prosecution Service in May 2007 with Alexander Litvinenko's poisoning.