A group of Scotland Yard detectives has started its work in Moscow as the probe continues into the death of Aleksandr Litvinenko. The arrival of the detectives holds out some hope that the mystery will be clarified.

“It is not clear how many people will be questioned, but it is known that one of them is Andrey Lugovoy, a former Russian security officer, who claims he himself has tested positive for radioactive materials after meeting Litvinenko in London,” said Anjoum Noorani, the press secretary of the British Embassy in Moscow.

Andrei Lugovoy said he is ready to talk to the Scotland Yard officers who are in Russian capital now. He made this statement from a Moscow hospital where he is being checked for radiation poisoning.

“I will talk to British investigators when they want me to. My lawyer says there are certain international procedures, according to which I should be correctly invited and then my evidence will be documented. I do not like the way the British press involved me in the case, but I can't comment more on it now, before I talk to the police. I'm undergoing medical tests now, the results will be known in the next few days. The only thing I can say is I am afraid of the radiation they found in me,” said Mr Lugovoy in an exclusive interview which he gave Russian Today from a hospital.

So, the questioning of Andrei Lugovoy will depend upon the doctors' decision.

Friends of Litvinenko also urged the British investigators to question another former Russian Security Service officer, Mikhail Trepashkin, saying he holds “key evidence” in the case.

Meanwhile Yuri Chaika, Russia’s Prosecutor General, said possible suspects in the killing of Aleksandr Litvinenko could not be extradited to Britain.

For the time being, the British Embassy in Moscow is being checked for radioactive materials.

As for the cause of Litvinenko's death, Russia's Defence Minister Sergei Ivanov said the information former Security officer Aleksandr Litvinenko obtained was not that significant.

According to the Russian minister, Mr Litvinenko was not a high ranking FSB official and did not have access to top-secret materials as he worked in a department which was in charge of organised crime activities.