Mr Gordievsky was a Soviet spy who defected to the West
Police have said they are investigating an alleged attempt to kill a former Russian spy who defected to the UK.
Surrey Police confirmed they were probing claims that Oleg Gordievsky was poisoned in November.
Mr Gordievsky told the Mail on Sunday he believed he was the target of an assassination attempt.
Mr Gordievsky, 69, a one-time KGB colonel who became the highest ranking Soviet spy to defect to the West, was honoured by the Queen last year.
In October, he was recognised for services to UK security and was made a Companion of the Most Distinguished Order of St Michael and St George.
In November, Mr Gordievsky was taken by ambulance from his Surrey home to a Guildford hospital after falling ill.
A Surrey Police spokeswoman said officers had been called to an address in November "following concerns for the safety of a man".
She went on: "The man, who was 69 at the time, was taken by ambulance to the Royal Surrey County Hospital for treatment.
"Surrey Police is continuing to investigate allegations made by this man and it would not be appropriate to comment further until our investigation is complete."
Mr Gordievsky's claims come in the wake of the murder of former security agent Alexander Litvinenko in London in 2006, and heightened diplomatic tensions between Russia and the UK.
The former spy said he was certain he was the victim of a similar assassination attempt to that which claimed Mr Litvinenko's life.
Escape to UK
Mr Gordievsky told the paper: "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 also accused MI6 of attempting to cover up the alleged crime.
The former spy explained that, after falling unconscious for 34 hours, he spent two weeks in a private clinic and was initially left partially paralysed.
Mr Gordievsky, who escaped to the UK in 1985, said he still has no feeling in his fingers as a result of what he believes was poison.
Disillusioned with the political situation in his homeland, he operated as a double agent during the Cold War.
He first began to leak information to the West while working in Copenhagen in 1974.
The former spy, who has two daughters, was MI5's greatest asset between 1982 and 1985, when his cover was blown.