Four men have been arrested in Luton this morning, on suspicion of committing offences under the Terrorism Act.
The men, who are all in their 30s, were arrested on suspicion of being involved in the "commission, preparation and instigation of acts of terrorism".
They have been taken into custody at a London police station.
Searches are now being conducted at seven separate addresses in the town, north of London, in connection with the investigation. A number of vehicles are also being searched, police said.
The arrests were carried out in a joint operation by the Met's Counter Terrorism Command (SO15) and the Eastern Counter Terrorism and Intelligence Unit (ECTIU).
Police said the arrests came as part of an "an ongoing proactive investigation concerning individuals in the Luton area" and were unrelated to the recent attacks in Paris, in which 129 people were killed.
We are not able to give further information at this time.