The decision of the British government to expel four Russian diplomats over the Kremlin's refusal to extradite a suspect in the poisoning death of a former KGB spy has been praised by an intelligence expert.

Britain's actions came after Russian prosecutors officially refused a request to extradite Andrei Lugovoi, a Russian businessman and former KGB agent accused in last year's fatal poisoning of former KGB agent Alexander Litvinenko.

"I thought that the British government has taken a very strong and appropriate action concerning the refusal of the Russian government to extradite Mr. Lugovoi," Russian intelligence expert Paul Joyal told CTV's Canada AM.

"Britain is underlying and reemphasizing the seriousness of this dreadful event and is taking even further steps to review the visa laws, the visa regulations between the U.K. and Russia as well as referring this case to the European council."

Russia has vowed it will respond Tuesday to Britain's decision to expel four Russian diplomats.

Many observers feel Russia's response may be a retaliatory set of expulsions, but speculation has also swirled around whether British economic interests will be targeted.

"London's position is immoral," Russian Foreign Ministry spokesman Mikhail Kamynin said in an Associated Press report Monday.

"They should understand well in London that the provocative actions conceived by British authorities will not go unanswered and cannot fail to produce the most serious consequences" for bilateral relations, he said.

The affair is indicative of a deteriorating relationship between Britain and Russia under President Vladimir Putin.

Litvinenko died in a London hospital on November 23 last year after becoming seriously ill. British investigators determined in May that they have enough evidence to prove that Lugovoi administered radioactive polonium-210 to Litvinenko at a hotel in London on Nov. 1.

In a deathbed note Litvinenko, a former KGB agent, blamed Putin.

However, Russian authorities have refused to extradite Lugovoi, citing a constitutional prohibition against turning over Russian citizens to foreign nations, as well as a European convention on extradition.

"I think that it is their reaction of not taking the British case seriously also underlines and heightens the suspicion that Mr. Lugovoi and other elements of the Russian government were indeed involved in this case," said Joyal.

Joyal, who was an acquainatance of Litvinenko,  was himself shot in the driveway of his home earlier this year -- four days after he suggested the Putin government was involved in his friend's death.

While Joyal did not conclusively state that his shooting may have been related to his criticisms he did not completely rule out the possibility.

"The fact that many people do believe and are convinced that it was retaliation that led to this attack is an indictment on current affairs in Russia," he said.

With files from The Associated Press