Foreign Secretary William Hague today said that Britain had asked the Russian Embassy in London to withdraw a staff member on December 10 "in response to clear evidence of activities by the Russian intelligence services against UK interests."
He said Russia, in return, expelled a diplomat from the British Embassy in Moscow.
The Russian Foreign Ministry and the Kremlin refused to comment when contacted by the Associated Press.
UK-Russia relations soured after the 2006 poisoning death in London of former Russian agent Alexander Litvinenko. Russia has refused to extradite Britain's main suspect in the case, former KGB officer Andrei Lugovoi.
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