Eleven British Muslims were jailed on Friday for planning what a court heard was an Al-Qaeda-backed plot to carry out a string of bombings that they hoped would rival 9/11 and the 2005 London attacks.

The conspiracy involved at least six of the plotters travelling to Pakistan for terror training, with the eventual aim of setting off eight rucksack bombs in crowded areas and possibly other timed devices.

Ringleader Irfan Naseer received a life sentence, his right-hand man Irfan Khalid was jailed for 18 years and co-conspirator Ashik Ali was jailed for 15 years by a judge at Woolwich Crown Court in southeast London.

Eight other members of the cell which was based in Birmingham, central England, were also sentenced on Friday.

"Your plot had the blessing of Al-Qaeda and you intended to further the aims of Al-Qaeda," Judge Richard Henriques said as he sentenced the men.

"The only barrier between (Naseer's) team and mass murder was the intervention of the authorities."

The terror cell was heavily influenced by the teachings of American-born Al-Qaeda preacher Anwar al-Awlaki, who was killed by a drone strike in Yemen in September 2011, police said.

Prosecutors said that the attacks planned by the men would have been the deadliest since the July 7, 2005 London bombings, in which 52 people were killed by three Islamist suicide bombers on subway trains and a fourth bomber on a bus.

Khalid meanwhile boasted that the attack would be "another 9/11", referring to the September 11, 2001 attacks on the United States, the trial heard.

The plot was also the most significant terror plan uncovered in Britain since the 2006 plot to blow up transatlantic airliners using bombs in drinks bottles, police said.

The judge said the attacks may have been intended to target Birmingham, although police said the planned location was not clear.

Naseer, a jobless 31-year-old pharmacy graduate nicknamed Chubbs because of his weight, and Khalid and Ali, both 28, were found guilty by a jury in February of engaging in conduct in preparation of terrorist acts.

Naseer and Khalid had visited Pakistan to receive terrorism training, while Naseer also helped four others to travel to the country for the same purpose, although the four had second thoughts on arrival in Pakistan and dropped out.

"Irfan Naseer was the leader, driving force and man in charge and he alone must take responsibility for sending four young men to Pakistan for terrorism training," the judge said, handing Naseer a life sentence with a minimum of 18 years.

The group's chief financier Rahin Ahmed, 26, was jailed for 12 years and will serve a minimum of six after pleading guilty to collecting money for terrorism and helping others to travel to Pakistan for terror training.

The group tried to fund their plot by posing as street collectors for a Muslim charity and raised £12,000 ($18,000, 14,000 euros) -- but then lost £9,000 playing foreign currency markets and had to apply for bank loans, the trial heard.

Ashik Ali's older brother Bahader, 29, was sentenced to six years and two other cell members, Mohammed Rizwan, 34, and Mujahid Hussain, 21, were jailed for four years each.

The four group members who travelled to Pakistan for terror training but had second thoughts -- Shahid Khan, 21, Khobaib Hussain, 21, Ishaaq Hussain, 21 and Naweed Ali, 25 -- were each jailed for 40 months.

The main plotters were arrested while headed for a takeaway meal in September 2011.

In addition to the loss of the money the group showed an amateurish side.

During the surveillance Naseer was heard talking about mixing poison into creams such as Vaseline or Nivea and smearing them on car handles to kill people, and about welding blades to a truck and driving it into people.

Naseer and Khalid were also recorded reminiscing about a time at the training camp in Pakistan when a "Pakistani guy, AQ (Al-Qaeda) guy" told them to hide under a tree for four hours to avoid a US drone flying overhead.

"Underneath the tree, the drone can't detect you, innit," Naseer said.

"So I'm lying underneath the tree innit, and the drones are right about me bro, and it's going (makes a sound like a drone) and I'm thinking any minute it's going to fire a missile."