Russian news agency Interfax has reported that Russia is expelling four British diplomats, citing the Foreign Ministry.
Foreign Ministry spokesman Mikhail Kamynin also said Russia would stop issuing visas to British officials and seeking British visas for Russian officials.
He said Russia would halt counterterrorism cooperation with Britain.
The Russian Foreign Ministry had summoned British Ambassador Anthony Brenton today as confrontation mounted over the radiation poisoning death of former KGB officer Alexander Litvinenko.
Mr Brenton said: “I met with Deputy Minister (Alexander) Grushko and we of course discussed the Litvinenko case. He gave me several notices for me to pass on to London. I won’t comment on the contents.”
After Russia refused to hand over Andrei Lugovoy, accused of killing Litvinenko in London, Britain announced on Monday that it would expel four Russian diplomats and place restrictions on visas issued to Russian government officials.
The first Russian response to the expulsions came on Tuesday from Grushko, who called the British moves “a direct path to confrontation and narrowing of the opportunities for interaction with Russia on a wide spectrum of issues.”
He said Russia would inform Britain very soon of its response, while Britain said that retaliation would not be justified.
Litvinenko, a fierce Kremlin critic, died on November 23 after ingesting radioactive polonium-210, and blamed Russian President Vladimir Putin on his deathbed.