Met Counter Terrorism detectives have arrested a 17-year-old on suspicion of terrorism and indecent image offences.
Officers arrested the boy in east London under the Police and Criminal Evidence Act at approximately 07.00hrs on Tuesday, 24 October.
He was arrested on suspicion of collection of material of a kind likely to be useful to a person committing or preparing an act of terrorism, contrary to Section 58 of the Terrorism Act 2000.
He was also arrested on suspicion of possession of indecent photographs of a child, contrary to Section 160 of the Criminal Justice Act 1988 and possession of extreme pornographic images, contrary to Section 63 of the Criminal Justice and Immigration Act 2008.
The teenager has been taken into custody at a central-London police station.
Officers are searching an address in east London.
The investigation relates to Islamist extremism.
