A man from Hertfordshire has been arrested by counter-terrorism police at Gatwick Airport after returning on a flight from Iraq.
The 44-year-old was questioned by specialist officers under stop-and-search powers after he disembarked from the plane on Thursday (9 February).
He was then arrested on suspicion of preparation of terrorist acts and taken to a central London police station.
A Met Police spokesman said on Friday the man, who has not been named, remains in custody.
They said: "Officers from the MPS Counter Terrorism Command (SO15) yesterday, Thursday 9 February, attended Gatwick Airport and stopped a 44-year-old man from Hertfordshire under schedule 7 of the Terrorism Act after he disembarked from a flight from Iraq.
"As a result of enquiries during the stop a decision was made to arrest the man under section 5 of the Terrorism Act – suspicion of preparation of terrorist acts.
"The man was arrested under PACE (Police and Criminal Evidence Act) and taken to a central London police station where he remains in custody."