Double agent Gordievsky claims he was poisoned by the Kremlin

Police are investigating allegations that a former Russian spy who defected to Britain was poisoned in an attempt to assassinate him.

Oleg Gordievsky spent 34 hours unconscious in hospital after falling ill at his home in Guildford in November. He was initially partially paralysed and still has no feeling in his fingers.

Mr Gordievsky, the highest-ranking Soviet spy to defect to the West, claimed he was the victim of a Kremlin-inspired assassination attempt similar to that alleged to have killed the former security agent Alexander Litvinenko.

"I've known for some time that I am on the assassination list drawn up by rogue elements in Moscow. It was obvious to me I had been poisoned," he told The Mail on Sunday. He accused MI6 of forcing Special Branch to drop its early investigations into his allegations.

Mr Gordievsky claims he was poisoned with thallium, a highly toxic metal used in insecticides which was favoured by the KGB in assassinations during the Cold War. Mr Litvinenko was poisoned with polonium, a radioactive element.

A police spokeswoman said: "Surrey Police were called to an address in Surrey on 2 November 2007 around 11.30am following concerns for the safety of a man. The man, 69 at the time, was taken by ambulance to the Royal Surrey County Hospital for treatment." She said the man's claims were being investigated and "it would not be appropriate to comment further until our investigation is complete".