A man has been arrested on suspicion of terrorism at Stansted Airport.
The 21-year-old was stopped at the airport under the Terrorism Act 2000 at 8.40pm on Sunday.
He was later arrested at 1.10am yesterday on suspicion of being involved in the commission, preparation and instigation of terrorism offences.
The man, who was returning to the UK from Istanbul in Turkey, via Stuttgart, has been taken to a London police station, where he remains in custody.
A Met Police spokesman said: "This arrest was not in response to any immediate threat or risk.
"Detectives have carried out searches of three addresses in connection with this investigation.
"Inquiries are ongoing and we are not able to give further detail at present."