Two Muslim radicals sentenced to prison on Tuesday for possessing documents useful to terrorists, including information on how to make weapons and explosives, may have been plotting to attack Britain's royal family, the Daily Telegraph reported. According to the report, the two were members of a cell that had information on the queen and the duke of Edinburgh, the prince of Wales, the duke of York, the earl of Wessex and the princess royal, as well as Princess Michael of Kent, the duke and duchess of Gloucester and the duke and duchess of Kent. Judge Timothy Pontius set a 12-year sentence for Aabid Khan, 23, who allegedly was a key figure in radicalizing young people, including an 18-year-old man - Hammaad Munshi, who was involved in the same case and faces sentencing next month. Munshi was the youngest person to be convicted of a terrorist offense in Britain, the Crown Prosecution Service said. "They had details of explosives and poisons along with information about London landmarks and a computer folder on royal residences. We would be foolish to rule out the fact that they may have been planning an attack," the Telegraph quoted one counterterrorism source as saying. Khan's codefendant, Sultan Muhammad, 23, was sentenced to 10 years in prison. Sentencing was interrupted by Khan's father, Sabir Khan, who accused the judge of being anti-Muslim. Khan was convicted by a jury on Monday of three counts of possessing articles for a purpose connected with terrorism. Muhammad was found guilty of three similar charges and a charge of making a record of information likely to be useful in terrorism. The prosecution said the two men had computer files promoting violent jihad, documents with practical information on making and using weapons and explosives, and one that urged assassinations. "If you can find a big target and take it out, like a military base in the UK, then praise be to Allah," the Telegraph quoted Khan as having told one Internet correspondent. "Our group is growing. We need to plan better and to adapt now a few more people are showing interest. We need to confirm and to encourage... I want to have a group of at least 12 if possible." Elsewhere, the report said, Khan wrote about explosives, saying, "You need to take care to store them in low temperatures, otherwise they can kill. They must not come into contact with fire, oil or detergent." Pontius said the defendants were not guilty of attempting or planning to attempt an act of terrorism, "but rather of possessing articles intending they should be used in some way at some future time of preparing and instigating acts of terrorism, the precise details of which, such as time and place, had yet to be finalized." However, the Telegraph quoted Detective Chief Superintendent John Parkinson, head of the Counter Terrorism Unit in Leeds, as saying that the men had posed a "very real threat." "Let there be no doubt, these are dangerous individuals," he was quoted as saying. "These men were not simply in possession of material which expressed extremist views. They were also in possession of material that was operationally useful to anyone wishing to carry out an act of violence or terrorism." Pontius added that the material seized by police "is amongst the largest and most extensive ever discovered and thus makes this case one of the most serious of its type to come before the courts." Prosecutors said Khan had enlisted Munshi, then 15, as a supporter of jihad. They said Munshi had downloaded detailed instructions for making napalm, other high explosives, detonators and grenades, and on "how to kill."