Student accused of planting bomb on London Tube train

Prosecutors say a university student with an interest in weapons and extremism planted a homemade bomb on a London subway train with the intention of causing carnage.

Damon Smith went on trial Wednesday, accused of placing an explosives-filled knapsack on a London Underground train in October.

Prosecutor Jonathan Rees told jurors at London's Central Criminal Court that Smith "built an improvised explosive device which he intended would explode and endanger the lives of those travelling on that Tube train or, at the very least, cause serious damage to the train itself."

Rees said the 20-year-old computer science student, who has a form of autism, had an interest in guns and explosives, and had searched online for Islamic State group material.

Smith claims the device was only meant to spew smoke.