Britain has been outlining the measures it is taking against Russia, in a row over the murder of the former Russian secret agent Alexander Litvinenko in London last year.
The UK has demanded the extradition of Andrei Lugovoy from Russia to Britain to stand trial for the killing.
Russia has refused, saying it is against the constitution.
The foreign secretary, David Miliband told the British parliament he will expel four Russian diplomats; review the way Russian embassy staff are issued visas; and suspend visa negotiations aimed at making travel to Britain easier for ordinary Russians.
Moscow has called the diplomatic expulsions immoral and provocative.
Lugovoy denies the murder, and maintains that Litvinenko was killed by the British secret service.
Litvinenko, who had become a UK citizen, was poisoned with the highly radioactive Polonium 210.
Traces of the substance were found in places visited by Lugovoy.
Sources in Moscow say they are preparing an adequate response to the British measures, stirring memories of the tit-for-tat expulsions of diplomats during the cold war.