Update | Missing Malaysia Airlines jet ‘may have flown on for four hours’, say US investigators

US investigators suspect the missing Malaysia Airline passenger jet was in the air for four after its last confirmed contact, and may have been diverted to an unknown location, it was reported on Thursday.

Aviation investigators and national security officials are basing their theory on data automatically downloaded and relayed to the ground from the Boeing 777’s Rolls-Royce engines, which suggested the plane flew for a total of five hours, The Wall Street Journal reported. It attributed the details to two unidentified sources "familiar with the details".

The missing Malaysia Airlines jet sent two bursts of technical data back to Rolls-Royce, to the plane’s engine maker’s global engine health monitoring centre, before it vanished off the radar, the New Scientist reported on Thursday.

If confirmed, it could aid the protracted investigation looking for clues that might pinpoint the last known movements of the Boeing 777-200ER.

Flight MH370 sent data as it took off from Kuala Lumpur International Airport, and subsequently during the plane’s climbing phase.

“US counterterrorism officials are pursuing the possibility that a pilot or someone else on board the plane may have diverted it toward an undisclosed location after intentionally turning off the jetliner’s transponders to avoid radar detection,” the WSJ reported, citing “one person tracking the probe”.