Cedric Belfrage ranked 'higher than Philby' by Soviets

Britain's security services were too embarrassed to prosecute one of their own intelligence officers after they got a tip off that Cedric Belfrage was passing secrets to Russian agents, according to documents released by The National Archives.

Belfrage, who died in 1990, worked as an intelligence officer for British Security Coordination in New York during World War 2.

His cover was blown in 1945 when a woman revealed Belfrage had been passing documents on to the KGB.

Belfrage was questioned and confessed to the FBI, but said the information he handed over was of no importance and that his bosses knew he was in contact with a US network of Russian spies.

However, Professor Christopher Andrew, who is MI5's official historian, told the BBC that in the middle of the Second World War, Soviet intelligence ranked the information Belfrage gave them ahead of secrets supplied by Kim Philby.