A 40-year-old woman has been arrested for suspected terrorism offences.
The woman was arrested in South London at 4.30am and taken to a police station, where she remains in custody.
She was arrested in connection with an alleged posting of extremist material online.
Police raided a residential property connected with her arrest, which still continues.
Officers are liasing with the Italian authorities following the arrest, after a 20-year-old Moroccan was arrested by Italian police for terrorism offences earlier today.