US intelligence agencies added the mother of the Boston bombing suspects to a government terrorism database 18 months before the bombings, two officials said.

The US government added the name of the dead Boston Marathon bombing suspect to a terrorist database 18 months before the deadly explosions, officials say.

The Twitter accounts of two popular television programmes in the US have been compromised and suspended.

The 19-year-old college student wanted over the Boston Marathon bombings is seriously ill in hospital and unable to be questioned after a manhunt that left the city virtually paralysed and his older brother and accomplice dead.

The suspect being hunted in the Boston Marathon bombing is in a boat stored in a Watertown neighbourhood, a law enforcement official says.