The Wall Street Journal broke the new developments after talking with two unofficial sources familiar with the American investigation - raising a whole new raft of questions about what happened to the jet which disappeared seemingly without trace from radar at around 1.30 am early on Saturday morning en-route to Beijing.
Government terrorism experts are now examining the possibility that the pilot or somebody else turned the plane's transponders off to avoid detection and flew it to another country.
A total flight time of five hours upon leaving Kuala Lumpur means that the Boeing 777 would have been able to remain airborne for an additional 2,200 nautical miles at its air-speed - which put the border of Pakistan and the Arabian Sea within its reach.