LONDON — Three young British Muslim men went on trial in London on Monday, accused of plotting to set off multiple bombs in terrorist strikes that prosecutors say could have been deadlier than the 2005 London transit attacks.

Prosecutors allege that the men, fired up by the sermons of a US-born Al Qaeda preacher, hoped to cause carnage on a mass scale. But their plot was undone by mishaps with money and logistics, and ended in a police counterterrorism swoop last year.