Russia's foreign ministry said on Friday it had given Britain one month to cut its diplomatic contingent in Moscow to the same size as the Russian diplomatic mission in Britain.
The ministry, in a statement, said it had summoned British ambassador to Moscow Laurie Bristow to the foreign ministry building and handed him a note of protest.
It said Britain's "provocative actions" had led to the decision by multiple Western governments to expel scores of Russian diplomats from their capitals.