The teenage son of a veteran of the Afghan jihad against the Soviet Army was convicted yesterday of possessing a bomb-making manual.

Abdul Patel, 18, was found guilty under the Terrorism Act of possessing an item that could prove useful to terrorists. But an Old Bailey jury acquitted him of the more serious charge of having the book for the purpose of committing a terrorist attack.

Patel, from East London, had protested that he was an ordinary teenager and played the jury his favourite rap video by Tupac Shakur.

The trial heard that his father, Mohammed Patel, had fought in Afghanistan in the 1980s and ran a charity shop that sent clothes and medical supplies to Chechnya and Bosnia. It was alleged that Patel helped out at the shop, which was known as a meeting place for Islamist extremists, but his defence team said he was no more than the “tea boy”. Patel clutched a copy of the Koran to his chest as the jury delivered its verdicts at the end of the three-week trial.

Judge Peter Rook, QC, granted him conditional bail until sentencing next month when, he said, a jail term could be imposed. The judge told the teenager: “You have been convicted of the serious matter of possessing this manual without reasonable excuse . . . I am keeping my options open. By granting bail I am not giving any indication of what my sentence will be.”

Patel was 17 and had been married for a few months when he was arrested and his home and other properties were searched in August last year. In a box marked “Don’t Touch” police found the book, entitled EOD (Explosive Ordinance Disposal), which had been printed in the US in 1990 to teach federal agents how to defuse devices.

Peter Wright, QC, for the prosecution, described the book as “a step-by-step guide to the manufacture and production of viable improvised explosive devices – homemade bombs”.

It included instructions on how to make explosives from fertiliser and ordinary household goods such as ammonia and iodine as well as information on the manufacture of letter bombs and simple fuses.

Mr Wright said that Patel’s finger-prints had been found on the book. He added: “Material such as this has a lasting utility, particularly in the hands of one as radicalised and motivated as this young man.”

The box also included letters from “martyrs” going to fight in Bosnia, a book on the Taleban and literature on the use of night vision binoculars.

Patel’s mobile phone had a picture of Osama bin Laden and the message “Kill Bush” on it. He said that much of the material was memorabilia from the war against the Soviet Union in Afghanistan. Patel will be sentenced on October 26.

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