US investigators suspect a missing Malaysian airliner was in the air for four hours after its last confirmed contact, and may have been diverted to an unknown location, the Wall Street Journal reported Thursday.
It said US aviation investigators and national security officials are basing their theory on data automatically downloaded and sent to the ground from the Boeing 777's Rolls-Royce engines, which suggested the plane flew for a total of five hours.
The WSJ attributed the information to two unidentified sources "familiar with the details". Contacted by AFP, Rolls-Royce in Singapore said it could not comment on an ongoing investigation.
"We continue to monitor the situation and offer our support to Malaysia Airlines," the British engine maker said in a statement from Singapore.
The report could mean that the Malaysia Airlines flight, which had 239 people on board, travelled for hundreds of miles after its last contact with air traffic control at around 1:30 am Saturday (1730 GMT Friday) -- about an hour after takeoff from Kuala Lumpur en route to Beijing.
Search teams are already covering a huge area comprising 27,000 nautical miles (more than 90,000 square kilometres), from the South China Sea to the waters west of Malaysia.
Malaysian investigators have made clear that they are still considering hijacking as one of their lines of inquiry and the CIA has not ruled out a terror link.
"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".
It went on to say that the uncertainty over the plane's course and why its transponders were not working "has raised theories among investigators that the aircraft may have been commandeered for a reason that appears unclear to US authorities".
Officials had been told that investigators were pursuing the theory that the plane was diverted "with the intention of using it later for another purpose", the WSJ quoted one source as saying.
New Scientist magazine also reported that Rolls-Royce had received "at least two bursts of technical data" from flight MH370 at its British monitoring centre in Derby, which keeps a real-time track of its engines in use on civilian aircraft around the world.
One of the data sets was sent on takeoff, the other during the climb towards Beijing, the magazine said on its website Wednesday.
It said the engine data was "filtered" from a larger report from the plane's Aircraft Communications Addressing and Reporting System (ACARS) system -- which puts out information about location and airspeed.
Malaysia Airlines has said that all its aircraft are equipped with ACARS, but has said that "no information was relayed" by the system installed on flight MH370 and that there was no distress signal from the cockpit.
Frustration over the shifting focus of the search and apparent lack of concrete information on the plane's flight path has led to accusations of a chaotic and confused response by the Malaysian authorities and the airline.