Britain's ambassador has issued a direct challenge to Russia over its refusal to extradite the man accused of killing Kremlin critic Alexander Litvinenko in London.

The Russian Foreign Ministry today expressed surprise that Russia was being accused of refusing to cooperate with Britain in the fight against terrorism, saying it was Britain that took the first “unfriendly” step.

Diplomatic relations with Russia will come under increasing strain today amid promises of retaliation for the expulsion of four of its UK diplomats.

Russian authorities have formally refused to extradite Andrei Lugovoy to face trial over the murder of Alexander Litvinenko.

Russia’s spy agency said today it has opened a criminal investigation into allegations by a Russian man that he was recruited by Britain’s foreign intelligence agency, MI6.

Russia has refused Britain’s request to extradite a suspect in the Alexander Litvinenko poisoning case, news reports said today.

Russia’s security agency today said that it has launched an investigation into suspected British spying, based on information from Britain’s chief suspect in the fatal poisoning of former agent Alexander Litvinenko.

Russia’s security agency has opened an espionage case in connection with claims made by Andrei Lugovoy, the suspect named by Britain in the radiation poisoning death of former agent Alexander Litvinenko in London last year.

The widow of poisoned former KGB agent Alexander Litvinenko says he was not working for British intelligence, as his alleged killer claims.

THE chief suspect in the killing of ex-KGB agent Alexander Litvinenko yesterday claimed British intelligence services had a hand in the poisoning.

The chief suspect in the killing of ex-KGB agent Alexander Litvinenko today claimed that British intelligence services had a hand in the poisoning – an assertion likely to further damage relations between Moscow and London.

The Russian businessman whom Britain has named as a suspect in the killing of ex-KGB agent Alexander Litvinenko today said he had evidence of British special services’ involvement in the death.

Andrei Lugovoy, named as a suspect in the radiation killing of ex-KGB agent Alexander Litvinenko in London, today said Britain tried to recruit him to provide intelligence.

The process of extraditing the man suspected of murdering Alexander Litvinenko was begun by prosecutors tonight.

Russia's top prosecutor told his British counterpart today that Russia could prosecute the chief suspect in the Alexander Litvinenko killing if Britain presents sufficient evidence, the Interfax news agency reported.

Poisoned former KGB man Alexander Litvinenko met two other Russian agents in Moscow in 1998 to make an extraordinary video in which they claimed their bosses had ordered them to kill, kidnap and frame prominent Russians.

A documentary about poisoned Russian spy Alexander Litvinenko will have its world premiere at the Cannes Film Festival in France this week, its co-director said today.

Russian businessman Andrei Lugovoy today said that British prosecutors' decision to charge him with the murder of Alexander Litvinenko is "politically motivated", news agencies have reported.

The Russian prosecutor-general’s office today said it would not turn over Andrei Lugovoy, charged by Britain in the poisoning death of Alexander Litvinenko, the Interfax news agency reported.

An ex-KGB agent is to be charged in connection with the murder of poisoned former Russian spy Alexander Litvinenko, the Crown Prosecution Service said today.

A SECOND Russian businessman who met murdered ex-spy Alexander Litvinenko on the day he fell ill is sick from radiation poisoning, local media quoted medical sources as saying yesterday.

A Russian man who met with Alexander Litvinenko on the day that the former KGB spy believed he was poisoned today said he had been questioned by British officials in Moscow, and again denied any involvement in his death.