The Russian authorities accused six British diplomats of spying and said they would be expelled, as tensions between Moscow and the West grow during an intensified push by Ukraine to loosen restrictions on using weapons provided by the US and Britain to strike Russia.

Russia’s Federal Security Service (FSB) said Friday it received documents indicating that the diplomats were sent to Russia by a division of the UK Foreign Office “whose main task is to inflict a strategic defeat on our country,” and that they were involved in “intelligence-gathering and subversive activities”.