Military radar data suggests a Malaysia Airlines jetliner missing for nearly a week was deliberately flown hundreds of kilometers off course, heightening suspicions of foul play among investigators, sources said Friday.

Analysis of the Malaysia data suggests the plane, with 239 people on board, diverted from its intended northeast route from Kuala Lumpur to Beijing and flew west instead, using airline flight corridors normally employed for routes to the Middle East and Europe, said sources familiar with investigations into the Boeing 777's disappearance.

Two sources said an unidentified aircraft that investigators believe was Flight MH370 was following a route between navigational waypoints when it was last plotted on military radar off the country's northwest coast.