Britain condemned Russia's refusal to extradite the main suspect in the murder of emigre Alexander Litvinenko as "unacceptable" yesterday and said it was reviewing cooperation with Moscow.

A spokesman for Prime Minister Gordon Brown said Russia's response was "extremely disappointing" and Britain was unsure that suspect Andrei Lugovoy, a former state security agent, would get a fair trial if it was held in Russia.

"We are reviewing the situation and considering what further steps we can take. We consider this a serious matter," the spokesman said, adding that all options were being considered.

"Russia is an important partner on many issues and we continue to seek a constructive relationship with them but given their refusal to co-operate on this matter, we need to carefully consider our range of co-operation on a range of issues."

Litvinenko, a former officer in Russia's Federal Security Service, fled to Britain and became a critic of President Vladimir Putin. He died in a London hospital last November after being poisoned with radioactive polonium-210.

British prosecutors confirmed Moscow had sent a formal refusal to extradite Lugovoy to face trial for the murder of Litvinenko.

A spokeswoman for the foreign office said: "We've consistently said that the murder of Mr Litvinenko is a serious criminal matter. The Russian reply is unacceptable."

Crown Prosecution Service (CPS) said the allegations against Lugovoy were that "he committed this extraordinarily grave crime here in our capital city".

Police found a trail of radiation matching Lugovoy's movements. But Lugovoy has denied any guilt, saying he believed Litvinenko had been killed by British intelligence.

(China Daily via agencies July 11, 2007)