MOSCOW - Russia said Thursday it was expelling four British diplomats in retaliation for a similar move by Britain, as a confrontation mounted between Moscow and London over the murder of former KGB agent Alexander Litvinenko.

After Russia refused to extradite Andrei Lugovoi, who is accused of killing Litvinenko in London, Britain said Monday it would expel four Russian diplomats and place restrictions on visas issued to Russian government officials.

Russian Foreign Ministry spokesman Mikhail Kamynin announced the British expulsions after British Ambassador Anthony Brenton was summoned to the ministry earlier in the day.

Kamynin described Russia's response as "targeted, balanced and the minimum necessary."

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.

"To our regret, cooperation between Russia and Britain on issues of fighting terrorism becomes impossible," he said.

Kamynin said the interests of tourists and businessmen would not be hurt. He said that on visa issues, Russia would mirror Britain's actions from now on.

Brenton said he met with Kamynin's deputy, Alexander Grushko. "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," Brenton said, the Interfax news agency reported.

Litvinenko, a fierce Kremlin critic, died Nov. 23 after ingesting radioactive polonium-210. From his deathbed, he said Russian President Vladimir Putin was behind his poisoning.