MOSCOW - Russia said Thursday it will expel four British diplomats and suspend counterterrorism cooperation with London, the latest move in a mounting confrontation over the radiation poisoning death of former KGB officer Alexander Litvinenko.

Britain had announced Monday the expulsion of four Russian diplomats and restrictions on visas issued to Russian government officials after Moscow refused to extradite Andrei Lugovoi, accused of killing Litvinenko in London last November.

Foreign Ministry spokesman Mikhail Kamynin announced the expulsions after summoning British Ambassador Anthony Brenton to the ministry and informing him.

Kamynin described Russia's response as "targeted, balanced and the minimum necessary." He contended that Russia was forced to respond, saying Britain had made a "conscious choice of worsening relations with our country."

Brenton relayed London's "continuing disappointment" with the Russian response.

Kamynin also said Russia would stop issuing visas to British officials and seeking British visas for Russian officials until London provides more information on the restrictions it has imposed.

"Until the new procedure is explained, Russian officials will not request British visas. And analogous requests by British officials will not be considered," he said.

He also said Moscow would suspend cooperation against terror.

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

He did not elaborate, and the extent of current cooperation -- with ties already damaged by Russian intelligence services' accusations of British spying -- was unclear.

Natalia Leshchenko, an analyst at the Global Insight think tank, said on BBC TV that Britain and Russia do cooperate against terror, but suggested the suspension was mainly meant to tarnish the new government of Prime Minister Gordon Brown in the eyes of its own people.

"The cooperation itself is there and we can also say it can be exaggerated if needed to show that Gordon Brown acts against the British people. At least that's what they are saying to the Russian public at the moment," Leshchenko 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.

"He has given me certain messages to deliver back to the foreign office, which I will now do," Brenton said. "I have underlined to him our continuing disappointment at Russia's reaction so far to our request for the extradition of Mr. Lugovoi and our continuing hope that Russia will find a way to cooperate."

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.