The Malaysia Airlines passenger jet may have flown for four hours after losing contact with air traffic controllers, reports the Wall Street Journal.
The Wall Street Journal said U.S. aviation investigators and national security officials believed the plane flew for a total of five hours, based on data automatically downloaded and sent to the ground from the Boeing 777's engines as part of a standard monitoring program.
If confirmed, the report would represent another dramatic twist in what is already one of the most baffling mysteries in modern aviation history- the fate of Flight MH370, which took off from Kuala Lumpur early on Saturday and dropped off civilian radar screens less than an hour into its flight to Beijing.
On the sixth day of the search, planes were sweeping an area of sea where Chinese satellite images had shown what could be debris, but had so far found no sign of the airliner.
It raises the possibility that the plane, and the 239 people on board, could have flown on for an additional distance of about 2,200 miles, potentially reaching Pakistan, destinations in the Indian Ocean or Mongolia, the Wall Street Journal said.
A senior Malaysia Airlines official told Reuters that no such data existed, while a second official said he was unaware of it. A spokeswoman for engine manufacturer Rolls-Royce had no immediate comment.
Malaysia Airlines has said previously that the Rolls-Royce Trent engines stopped transmitting monitoring signals when contact with the plane was lost.