LONDON — Three British Muslim men went on trial in London on Monday, accused of plotting a bombing campaign that prosecutors say could have been deadlier than the 2005 London transit attacks.

Prosecutors say Irfan Khalid and Ashik Ali, both 27, and 31-year-old Irfan Naseer were part of a plot to mount a terrorist attack "on a scale potentially greater than the London bombings in July 2005."

Fifty-two commuters were killed when four al-Qaida-inspired suicide bombers blew themselves up on London's bus and subway network on July 7, 2005.

The suspects are among a group of men and one woman arrested in September 2011 in the central English city of Birmingham.

All three are charged with preparing for terrorism by plotting a bombing campaign, recruiting others and fundraising. Khalid and Naseer also are accused of traveling to Pakistan for terrorism training.

They have entered innocent pleas.

Prosecutor Brian Altman said the three were central figures in a plan to detonate up to eight knapsack bombs in a suicide attack, or to explode timer bombs in crowded areas.

Prosecutors say targets and other details had not been finalized when the men were arrested.

The three were allegedly inspired by the anti-Western sermons of U.S.-born Islamist cleric Anwar al-Awlaki, who was killed in Yemen in September 2011.

Altman said Naseer and Khalid traveled to Pakistan for terror training, where they learned details of poisons, bombmaking and weapons use and made "martyrdom videos" justifying their planned attacks.

On their return in July 2011, he said, they began to recruit others to the plot and to raise money by posing as fundraisers for Muslim charities.

They also began experimenting with chemicals "to make an explosive mixture for use in an improvised explosive device," the prosecutor said.