A man has been arrested by counter-terror police on suspicion of spying.
The suspect, who is in his 40s, is accused of spying in Britain for Vladimir Putin, according to The Sun.
The man was arrested under the Official Secrets Act at Gatwick Airport on Monday evening.
He was due to get an outbound flight when he was arrested, the newspaper reported.
Scotland Yard said he had been detained under section one of the act.
The spokesman said: “He has been taken to a London police station, where he remains in police custody. Inquiries continue.”
Section one of the act relates to information contained within notes, plans or sketches that may be useful to an enemy.
Under the Official Secrets Act, a person can be guilty of an offence if they make a “damaging disclosure of any information or document” relating to security or intelligence.