A Swedish woman has been arrested at Gatwick airport on suspicion of committing a terrorism offence.
The 40-year-old was held under terrorism laws just before 2.15pm on Thursday after arriving on a flight from Italy, police said.
The south-east counter-terrorism unit said she was later arrested under section 41 of the Terrorism Act 2000 on suspicion of commission, preparation or instigation of acts of terrorism.
Her arrest is understood to be related to the Islamic State group. She remains in police custody.