Legendary British spy and Soviet double agent George Blake, has died aged 98, Russia's Foreign Intelligence Service Spokesman Sergey Ivanov told Sputnik.

"We have received bitter news, the legendary George Blake is gone," Ivanov said.

Blake, born in Rotterdam, was a British spy who worked as a double agent for the Soviet Union during the Cold War.

He became a Communist and decided to work for the KGB while a prisoner during the Korean War.

The 98-year-old spy had been living in Moscow since he escaped from Wormwood Scrubs in 1966.

Blake was sentenced to 42-year jail in London in 1961 for spilling British secrets to the Soviet Union. He went on the run after climbing over the London prison’s wall in 1966.

Later he crossed into East Berlin and into the hands of his grateful Soviet spymasters.

“He died of old age, his heart stopped,” said spokesman for the SVR foreign intelligence agency, formerly the KGB.

Blake marked his 98th birthday last month with a message from spymaster Sergey Naryshkin who said: “From the chiefs of SVR and me personally please accept warm and sincere wishes.”

At his death he was the oldest KGB veteran.

Despite being a fugitive from justice in Britain since 1966, he kept in contact with the three sons he deserted when he fled to Moscow via East Berlin.