The Malaysian prime minister has said that new information tells with a "high degree of certainty" that communications of the plane that went missing a week ago was disabled just before the aircraft reached the east coast of Malaysia.
Najib Razak said on Saturday that the movements of the aircraft were "consistent with deliberate actions" by someone on the plane.
In only his second public statement since the jet went missing on March 8, Razak said investigators were looking into all possible scenarios of the plane's disappearance and that he hoped the latest information would lead to a breakthrough.
Razak said: "We have put our national security second to the search for the plane. This has been a situation without precedent. At every stage we have acted on the basis of verified information and we followed every credible lead. Sometimes these leads have led nowhere."
"There has been intense speculation. On behalf of those watching we have a responsibility to the investigation to only release information that has been corroborated."
Steve Preteska, an aviation safety expert, also told Al Jazeera that "it's too early to come up with a specific theory".
But he said that it is possible to turn off the airplane's transponder, a device which wirelessly transmits and receives electrical signals, from inside the cockpit.
"There is an on/off switch on the face of the unit. So it is conceivable that somebody, with access to that faceplate of the equipment, could turn the unit off."
Two possible corridors
Based on new information from Malaysian authorities and their international partners, said Razak, the plane's last communication with satellites was in one of two possible 'corridors'.
The first was a northern corridor stretching approximately from the border of Kazakhstan and Turkmenistan to northern Thailand. The second was a southern corridor stretching approximately from Indonesia to the southern Indian Ocean.
|Expert wary of early theories on missing plane
He said: "In view of this latest development the Malaysian authorities have refocused their investigation into the crew and passengers on board. Despite media reports that the plane was hijacked, I wish to be very clear: we are still investigating all possibilities as to what caused MH370 to deviate from its original flight path."
Flight MH370 has 239 people on board and more than 150 of them are Chinese.
There has been no sighting of the Boeing 777 since it disappeared from the radars and no debris has been found.
The search operation includes 57 ships and 48 aircraft and covers the Strait of Malacca, the Indian Ocean and the Andaman Sea. Razak said the search area would no longer include the South China Sea.