LONDON — A teenager accused of planting a bomb that partially detonated on a crowded London subway train last year has gone on trial in London.

Iraqi-born Ahmed Hassan is accused of making a homemade bomb and leaving it on a subway hidden in a plastic bucket inside a supermarket bag in September, injuring 30 people.

The 18-year-old is charged with attempted murder and using the chemical compound TATP to cause an explosion. He has denied the charges.

Prosecutors said Wednesday there were 93 people in the train car when the bomb partially exploded during the morning rush hour.

Officials said there would have been many more injuries and probably deaths if the device had operated properly.