“I wish to be very clear, we are still investigating all possibilities as to what caused MH370 to deviate from its original flight path,” he told a press conference at Sama-Sama Hotel, KLIA, Saturday.
Najib added that national security was second to the search for the missing plane.
“Based on new satellite information, we can say with a high degree of certainty, that the Aircraft Communication Addressing and Reporting System (Acars) was disabled just before the aircraft reached the east coast of Peninsula Malaysia,” he said.
Shortly afterwards, the aircraft transponder near the border between Malaysia and Vietnamese air traffic control was switched off.
From this point onwards, the Royal Malaysian Air Force primary radar data showed that an aircraft, which was believed but not confirmed to be MH370, did indeed turn back.
It then flew in a westerly direction back over Peninsula Malaysia before turning northwest.
“Today, based on raw satellite data which was obtained from the satellite data service provider, we can confirm that the aircraft shown in the primary radar data was flight MH370,” said Najib.
According to the new data, the last confirmed communication between the plane and the satellite was at 8.11am Malaysian time on Saturday, March 8.
Najib's update came as the hunt for MH370 entered its second week.
The aircraft’s communication with the ground was severed under one hour into its flight on March 8 from Kuala Lumpur to Beijing.
Wire services had earlier reported that the Boeing 777-200ER piloted by Captain Zaharie Ahmad Shah, 53 and co-pilot Fariq Abdul Hamid, 27 with 227 passengers and 10 other crew members could have been hijacked.
A Malaysian government official confirmed the investigators’ conclusion that one of the pilots or someone else with flying experience had hijacked the aircraft.
The official, who is involved in the investigation, said no motive had been established and it is not yet clear where the plane was taken.
According to reports, the official spoke on condition of anonymity because he was not authorised to brief the media.
The official had said that hijacking was no longer a theory: “It is conclusive.”