Malaysian Prime Minister Najib Razak said Saturday that no conclusive evidence shows missing Malaysia Airlines Flight MH370 was hijacked.

But the Boeing 777 aircraft did turn back from its last known location on civilian radar, and the signal the Malaysian military radar picked up at the north of the Strait of Malacca was from the missing plane, he added.

He said there is a high degree of certainty that the communication device aboard the plane was disabled and its movement showed deliberate action.

Investigators are still exploring all possibilities about its disappearance, stressed the prime minister.