A fire in the aft section of SpaceX's Starship trigged the apparent explosion that destroyed the spacecraft, the company says.

The US has grounded SpaceX's giant Starship rocket while an investigation is carried out into why it exploded during its latest test flight. The rocket's upper stage dramatically broke up and disintegrated over the Caribbean after launching from Texas on Thursday, forcing airline flights to alter course to avoid falling debris.

The "rapid unscheduled disassembly" was likely caused by a propellant leak, Elon Musk said, and was captured on video by spectators on the ground.