British authorities have filed charges against the first of four suspects in the attempted bombings on London's public transport system on July 21.

Officials say 24-year-old Yassin Hassan Omar is charged with conspiracy to murder and possession of an explosive substance. He was arrested July 27 in the northern city of Birmingham.

Two other July 21 suspects are in custody in London, and a fourth is held in Italy.

None of the bombs exploded in the attacks, which came two weeks after four bombers killed themselves and 52 others on three London subway trains and a bus.