Terrorist plotters from Birmingham planned to detonate a series of suicide bombs in an attack that could have been bigger than the July 7 atrocities, a court has heard.

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. In one conversation, Naseer was heard agreeing that the July 7 attacks had not done enough damage because there were no nails in the bombs.

The two men, along with Ashik Ali, also 27, are accused of being “central figures” in the alleged extremist plot.

Ali told police in 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 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.

Nasser 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.

The trial continues on Tuesday.