Detectives from the Met Police Counter Terrorism Command have arrested a man in Luton on suspicion of being involved in terrorism.
They arrested the 25-year-old man under section 41 of the Terrorism Act 2000, at approximately 6.10am ton Wednesday morning.
He is now being held in custody at a south-London police station.
Police are searching two addresses in Luton in connection with the investigation.
There is no immediate risk to the public.
Enquiries are ongoing.