A knife-obsessed teenager who talked about carrying out a terror attack with a blade or acid has been jailed for three years and four months.

Sudesh Amman, 18, was sentenced at the Old Bailey after he pleaded guilty to possessing and distributing terrorist documents.

His stash of manuals on bomb-making, knife-fighting and close combat included the titles Bloody Brazilian Knife Fighting and How to Make A Bomb In Your Kitchen.

Amman, of Harrow, north-west London, posted al-Qaida propaganda on a family WhatsApp group, exposing siblings as young as 11 to graphic material.

He also shared bomb-making literature via Skype chat.

The North West London College student jotted down how to make explosives and outlined his "goal" to be a martyr in a notebook, the court heard. Prosecutor Kelly Brocklehurst said police were alerted by a Dutch blogger who identified extremist material in a Telegram chat in April.

There was a photo of a knife and two firearms on a Shahada flag bearing Arabic words which mean "armed and ready". The blogger thought the same person also posted a YouTube link to a pro-gay rights speaker at Speakers' Corner in Hyde Park, the court heard.

Police linked the online post to Amman and arrested him in May. In a search of his family home, officers seized an air gun, a black flag and a combat knife.

Mr Brocklehurst said: "The defendant had discussed with his family, friends and girlfriend his strong and often extreme views on jihad, the kuffar, and his desire to carry out a terrorist attack.

"Much of his fascination with conducting an attack was focused on using a knife but reference was also made to committing acid attacks on mopeds.

"The Crown contends that the defendant's interest in Islamic extremism and Daesh in particular is more than a mere immature fascination with the taboo and with graphic violence. He is clearly someone with sincerely held and concerning ideological beliefs which motivate him to collect and disseminate such material.

"For example, he is seen telling his girlfriend in online chat how he has declared a pledge to Islamic State and wishes to purge society and carry out acid attacks. Elsewhere he is seen telling her he prefers the idea of a knife attack over use of bombs."

Last month, Amman entered guilty pleas to six charges of possession and seven of disseminating terrorism documents. Amman denied three charges, which were ordered to lie on court file.

The science and maths student had previous convictions for possession of an offensive weapon and cannabis. He was aged just 17 when he began collecting terrorist material in 2017.

Sentencing, Judge Mark Lucraft QC said: "This is a very concerning series of offences."

The defendant smiled and waved at the public gallery as he was sent down. Acting Commander Alexis Boon, head of the Metropolitan Police Counter Terrorism Command, said Amman had a "fierce interest in violence and martyrdom".

He said: "His fascination with dying in the name of terrorism was clear in a notepad we recovered from his home. Amman had scrawled his 'life goals' in the notepad and top of the list, above family activities, was dying a martyr and going to 'Jannah' - the afterlife.

"It's not clear how Amman became radicalised but it is apparent from his messages that it had been at least a year in development. Whatever the circumstances, this case is a reminder of the need to be vigilant to signs of radicalisation and report it."

By Emily Pennink