A teenager from Wiltshire has been convicted of terrorism for planning to attack a mosque and kill 10,000 people.

The 17-year-old was given a 24-month rehabilitation order and ordered to pay a £22 court surcharge at Southampton Youth Court after pleading guilty to possessing material likely to be useful to a person committing or preparing an act of terrorism. 

He was arrested on June 18 and during a search of his property detectives uncovered a handwritten note called 'The Big Plan'.

"This contained details of how to make a bomb, a number of named locations and individuals who were believed to be aspirational targets, and an intention to kill in excess of 10,000 people," a spokesperson from Counter Terrorism Policing South East (CTPSE) told the BBC. 

They added that "concerned" members of the public had reported the boy after he had made "numerous racist comments" in online forums. 

Detective chief superintendent Kath Barnes, head of CTPSE, praised the people who had contacted the anti-terrorism hotline to report the behaviour.

"I know this case may be concerning to certain members of the community who were the target of the atrocious hatred," she said.

"We have seen an increase in the proportion of our investigations from the threat from extreme right-wing terrorism who wish to cause harm in our communities.

"We take that threat very seriously and this is why the whole of the counter-terrorism community, as well as the whole of society, has a role to play in tackling it."

Wiltshire Police's assistant chief constable, Deb Smith, said: "I hope that our communities feel reassured that we acted swiftly, in conjunction with our partners, to ensure that this individual was detained and could no longer pose a risk to the wider public."