Detectives from the Met Police Counter Terrorism Command are investigating after four men at Luton Airport were arrested on suspicion of membership of a proscribed organisation, contrary to section 11 of the Terrorism Act 2000.
The men, who are all Sri Lankan nationals, arrived on an international flight on the evening of Wednesday, 10 April.
Police at the airport were made aware of the men the next day, Thursday, 11 April and subsequently stopped them under Schedule 7 of the Terrorism Act 2000. The men were then each arrested under the Police and Criminal Evidence Act 1984s.
All four men are currently in custody at a police station in Bedfordshire.
Enquiries are ongoing.