LONDON — The ringleader of an Al Qaeda-inspired plot to detonate knapsack bombs in England was sentenced on Friday to at least 18 years in jail.
Judge Richard Henriques said 31-year-old Irfan Naseer was ‘‘the leader, driving force, and man in charge’’ of the elaborate plot, sentencing him to life with no possibility of parole for 18 years.
‘‘Your plot had the blessing of Al Qaeda and you intended to further the aims of Al Qaeda,’’ Henriques told Naseer in London as he sentenced the man nicknamed Big Irfan, or Chubbs, along with 10 accomplices. ‘‘Clearly nothing was going to stop you, short of intervention of the authorities.’’
Prosecutors had said the men, fired up by the sermons of US-born Al Qaeda preacher Anwar al-Awlaki, hoped to cause carnage on a mass scale. One of Naseer’s accomplices was recorded calling the planned attack ‘‘another 9/11.’’
Police said the terrorist conspiracy was the most significant uncovered in Britain since a plot to blow up airliners in midair was foiled in 2006.
But the plot was undone by problems with money and logistics. No targets had been chosen and no bombs built when Naseer, Ashik Ali, and Irfan Khalid, both now 28, were arrested in September 2011 in Birmingham, central England, after a huge investigation and surveillance operation by police and the security service.
Prosecutors said Naseer and Khalid had traveled to Pakistan for terrorist training, where they learned details of poisons, bomb-making, and weaponry, and made ‘‘martyrdom videos’’ justifying their planned attacks.
On their return to England in July 2011, they began to recruit others to the plot and to raise money by posing as street collectors for Muslim charities.
They also began experimenting with chemicals, the prosecution said, aided by Naseer’s university degree in pharmacy.
But many of the group’s plans soon went awry. Four other young men dispatched by the plotters to Pakistan for terrorist training were sent home within days when the family of one man found out. The four pleaded guilty to terrorism-related offenses.
Rahin Ahmed, an alleged coconspirator described in court as the cell’s ‘‘chief financier,’’ tried to increase the group’s budget by trading the money it made from bogus charity fund-raising on the financial markets. Instead, he lost the bulk of the terror cell’s money.
Among the pieces of evidence at the four-month trial was a sports injury cool pack, which prosecutors said Naseer had mistakenly believed would contain ammonium nitrate, a key bomb-making ingredient.
The group also considered other outlandish attacks, including tying sharp blades to the front of a truck and driving it into a crowd. Naseer was heard talking about the possibility of mixing poison into creams such as Vaseline or Nivea and smearing them on car handles to cause mass deaths.
Prosecutors said the men ultimately gravitated toward a plan to detonate up to eight knapsack bombs — either on timers or in suicide attacks — in a bid to cause destruction on a scale larger than the July 7, 2005, London transit bombings, which killed 52 commuters.
Naseer was recorded plotting about knapsack bombs going ‘‘boom, boom, boom everywhere,’’ while Khalid said the attack would be ‘‘revenge for everything, what we’re doing is another 9/11.’’
The trio was convicted in February of plotting terrorist attacks and sentenced Friday at Woolwich Crown Court, with Khalid getting a minimum of 12 years in prison and Ali a minimum of 10 years.
Eight others who had pleaded guilty to involvement also were sentenced.