A Pakistani-origin British teenager was on Friday sentenced to two years in prison for compiling information likely to be useful to terrorists, becoming the youngest person in the UK to be convicted of terrorism.

Eighteen-year-old Hammad Munshi, who was arrested two years ago, was found guilty last month after the Blackfriars crown court in London [Images] heard how he downloaded files from the Internet about making napalm, detonators and grenades.

Sentencing him on Friday at the Old Bailey to two years in a young offenders' institution, Judge Timothy Pontius said that the teenager "fell under the spell of fanatical extremists."

"There is no doubt that you knew what you were doing," he said, adding the nature of the material Munshi downloaded made it "a particularly serious offence".

The judge said he had taken Munshi's age into account while handing down the sentence, but added that "it is plainly a case where deterrence must be in the forefront of the court's mind."

The schoolboy, grandson of a leading Islamic scholar from Dewsbury in West Yorkshire, was arrested on his way home from a GCSE chemistry exam in 2006 and found with two small bags of ball-bearings -- a key component of a suicide vest.

His grandfather Yakub Munshi is president of the Islamic Research Institute of Great Britain at the Markazi Mosque in Dewsbury.

Munshi's others associates -- Aabid Khan and Sultan Muhammad, both 23 -- were earlier sentenced to longer prison terms for possessing items for terrorist purposes.