Three men from Birmingham are accused of planning a suicide bombing campaign that according to the prosecution could have been more deadly than the 2005 London attacks.
They were allegedly plotting to detonate up to eight rucksack bombs in crowded areas to cause mass casualties.
It is claimed that two of them recorded suicide videos in Pakistan for use after their deaths.
Irfan Naseer, 31, and Irfan Khalid, 27, travelled to Pakistan for terrorist training before returning to the UK in July last year, jurors at Woolwich Crown Court were told.
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. Brian Altman QC
In one conversation, Naseer was heard agreeing that the 7 July attacks in the capital had not done enough damage because there were no nails in the bombs.
The two men, along with Ashik Ali, 27, are accused of being “central figures” in the alleged plot.
Ali told police in an interview that the plan had involved him wearing a suicide vest as well as carrying a gun, the jury heard.
The group also discussed the use of poisons and attaching blades to the side of a vehicle before driving it into a crowd of people, it is claimed.
Prosecutor Brian Altman QC told the court: “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 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.
Nasser and Khalid are also accused of travelling to Pakistan for terrorist training.
While in Pakistan, prosecutors claim Naseer and Khalid received training in how to use weapons and make bombs and poisons.They are alleged to have made suicide videos while they were there.
After they returned to Britain 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, and one woman, were arrested over the alleged plot.