A teenager who was 16 when he was arrested at Heathrow Airport has been jailed after being convicted of providing cyber-security support to groups including al-Qaeda.
Yusuf Shah, from Ilford, was also found to have downloaded documents including instructions on how to make explosives and how to use different types of weapons.
Analysis of Shah's phone found that he had accessed an online magazine published by al-Qaeda that contained information on how to carry out acts of terrorism, and had engaged in chat groups where he offered technical help.
Cdr Helen Flanagan, head of Counter Terrorism Policing London, said the case should act as a "warning to parents and carers to be aware of what their children are doing online".
Shah, who was stopped at Heathrow Airport in London under schedule 7 of the Terrorism Act in January 2024, was convicted at Kingston Crown Court and sentenced to four years and two months in prison.
Cdr Flanagan said the police investigation found Shah was being drawn into extremist material and ideologies "when he was only 13 or 14 years old".
She added: "This is reflective of a growing trend of young people being radicalised and accessing extremely dangerous and violent terrorist ideologies and material online."
Shah, who is now 18, had downloaded documents providing instructions on the use of different types of weapons, the Metropolitan Police said.
He had also engaged in chat groups that supported terrorist groups, on the messaging app Telegram.
At one point, the teenager advised members of the group on how to use an untraceable cryptocurrency to make a donation to al-Qaeda.
In March 2024, Shah was approached by an individual on the Telegram app to help produce a guide to cyber-security for Tehrik-e-Taliban (TTP), a terror group. The individual said a senior official within TTP had asked him for this.
Shah produced and sent the individual a document he titled "A Guide on Cybersecurity" that provided detailed information and instruction on cyber-security and the use of cryptocurrency.
He had been convicted of three counts of collecting terrorist materials, one count of entering or becoming concerned in an arrangement to make funds available for terrorism, and one count of providing instruction intended for use in terrorist activities.
Flanagan said: "Even at the age of just 16, Shah had enough knowledge of the online world to be able to provide practical advice to terrorist groups on how to make anonymous cryptocurrency payments."
She added: "I would implore you to have conversations, to be inquisitive about what your children are doing online."