A man was arrested at Gatwick Airport on suspicion of preparing terrorist acts after disembarking a flight from Iraq, Scotland Yard said.
The 44-year-old suspect, from Hertfordshire, was detained at the West Sussex airport yesterday by officers from the Metropolitan Police's Counter Terrorism Command (SO15).
A Scotland Yard spokesman said the man was held under Section 5 of the Terrorism Act - suspicion of preparation of terrorist acts - and is in custody at a central London police station.
Meanwhile, a 31-year-old man arrested in Norfolk on suspicion of fundraising for the purposes of terrorism and encouraging support for a banned terror group has been bailed to a date next month.
Scotland Yard said the arrest was related to suspected activities overseas, and that searches at two properties in east Norfolk and one in north London had been completed.