A 21-year-old man has been arrested on suspicion of being involved in the commission, preparation and instigation of terrorism offences.
The man was stopped at Stansted Airport at 8.40pm on Sunday after returning to the UK from Turkey, via Stuttgart.
The arrest was made by officers from the Metropolitan Police’s Counter Terrorism Command and was not in response to any immediate threat or risk, Scotland Yard said.
Detectives have carried out searches of three addresses in connection with the investigation, a police spokesman said.
A Scotland Yard spokesman could not confirm if the man arrested was suspected of travelling to Syria.