Investigators say the missing Malaysia Airlines jet was hijacked and steered off-course.
A Malaysian government official said people with significant flying experience could have turned off the flight's communication devices.
The representative said that hijacking theory was now 'conclusive', and police are now believed to be searching the home of pilot, Capt. Zaharie Ahmad Shah, in Kuala Lumpur.
While Malaysian Prime Minister Najib Razak refused to confirm that flight MH370 was taken over, he admitted 'deliberate action' on board the plane resulted in it changing course and losing connection with ground crews.
The plane's communication system was switched off as it headed East over the Malaysian seaboard and its last known location was pinpointed six-and-a-half hours later than first thought.
It is not yet clear where the plane was taken, however Mr Razak said the most recent satellite data suggests the plane could have headed to one of two possible flight corridors.
One possibility is the northern corridor, which stretches from the border of Kazakhstan and Turkmenistan to northern Thailand, while the other is the southern corridor from Indonesia to the Southern Indian Ocean.
The last radar contact was made along one of these paths, but the plane could have diverted from this point.
The aircraft's fuel reserves mean it could have travelled as far as Pakistan, Sri Lanka or Australia in the other direction.
However, if it was diverted into the Indian Ocean, the task of the search teams becomes more difficult, as there are hundreds of uninhabited islands and the water reaches depths of around 23,000ft.