A man has been arrested on suspicion of terrorism offences at Heathrow Airport.
He had just arrived on a flight from Turkey before his arrest, which police described as “Syria-related”.
The 26-year-old is being held by on suspicion of preparation of terrorist acts.
Met Police said the man was detained under criminal rather than terrorism legislation which means he can only be held for 24 hours or 36 hours with a superintendent’s approval.
Anyone arrested under the Terrorism Act can be held without charge for up to 14 days.
A spokeswoman for the Met said it was “quite common” for terrorism suspects to be detained under criminal, rather than terrorism legislation.