Sources say air traffic controllers at Tokyo's Haneda Airport say they were unaware the Japan Coast Guard plane involved in a recent fatal collision with a passenger aircraft had moved onto the runway after they directed it to proceed to a holding point on a taxiway.

The controllers also say they were not paying attention to the coast guard plane because they were occupied with other tasks such as coordination of other aircraft.

The controllers made the remarks during an interview with transport ministry officials.

The coast guard plane is believed to have mistakenly entered the runway where the collision took place.

The transcript of radio communications between air traffic control and the two aircraft does not contain any warnings to the planes about an abnormal situation.

Inspectors from the Japan Transport Safety Board have been questioning relevant people to determine what happened in the run-up to the collision.

A Japan Airlines passenger jet collided with the coast guard plane immediately after it landed on Tuesday. Both planes burst into flames.

Five of the six coast guard members on board died. The surviving pilot sustained serious injuries.

All 379 passengers and crew on the JAL plane were evacuated safely. Fifteen passengers who sustained injuries or felt unwell received medical treatment.