The Mail on Sunday reported Gordievsky was found unconscious in his home in Surrey County last year and after recovering, the former spy alleged he had been poisoned by a Russian citizen who had visited his safe-house.

"They murdered my friend Alexander Litvinenko," said Gordievsky, referring to the former Russian spy who was killed in London in 2006. "I have no doubt my sudden illness last November was a similar attempt on my life.

"It was obvious to me I had been poisoned."

Surrey police officially confirmed Saturday an investigation into Gordievsky's claims was under way, the Mail said.

The 69-year-old former KGB agent worked for more than 10 years as a double agent for British intelligence officials before defecting to Britain in 1985.