Three terrorist plotters led a plan to set off eight suicide bombs which could have been bigger than the July 7 London attacks, a court has heard.
Irfan Naseer, 31, Irfan Khalid and Ashik Ali, both 27, are accused of being "central figures" in the extremist plot, jurors at Woolwich Crown Court were told.
Prosecutor Brian Altman QC said: "The police successfully disrupted a plan to commit an act or acts of terrorism on a scale potentially greater than the London bombings in July 2005 had it been allowed to run its course. The defendants were proposing to detonate up to eight rucksack bombs in a suicide attack and/or to detonate bombs on timers in crowded areas in order to cause mass deaths and casualties."
All the men are accused of engaging in conduct in preparation of terrorist acts, which they deny.
Naseer is accused of five counts of the offence, Khalid four and Ali three, all between Christmas Day 2010 and September 19 2011.
For Nasser, from Sparkhill, Khalid, from Sparkbrook, and Ali, from Balsall Heath, all in Birmingham, this is alleged to have included planning a bombing campaign, collecting money for terrorism and recruiting others for terrorism. Naseer and Khalid are also accused of travelling to Pakistan for training in terrorism and it is alleged that Naseer also helped others to travel to the country for the same purpose.
It is alleged that, while in Pakistan, Naseer and Khalid received training in how to use weapons and how to make bombs and poisons, and made suicide videos while they were there. They returned to the UK in July 2011, and it is claimed the group then began trying to make home-made bombs, using a flat in Sparkbrook as their base.
In total, 11 men of Pakistani and Bangladeshi origin were arrested over the alleged plot, and one woman. Mr Altman told the jury that the three defendants were "central figures" in the plan, and that they are "jihadists". He called the trio "senior members of a home-grown terror cell".
Naseer has a degree in pharmacy and it is alleged that this knowledge helped the plotters to try to make explosives. Mr Altman said: "It was Naseer's knowledge of chemistry, together with his training as a terrorist in Pakistan, that allowed the defendants to experiment in preparing an explosive mixture with a view to constructing a home-made explosive device."
The group is also accused of making bogus charity collections in Birmingham for Muslim Aid as well as a local Muslim centre. But the two causes received only a fraction of the money they had collected, prosecutors say, while the rest was intended to fund the attack plan. Mr Altman said they were "despicably stealing money from their own community donated to charity".