AP TELEVISION

1. Malaysian Prime Minister Najib Razak entering news briefing

2. SOUNDBITE (English) Najib Razak, Malaysian Prime Minister:

"Based on new satellite communication, we can say with a high degree of certainty that the Aircraft Communications Addressing and Reporting System, or ACARS, was disabled just before the aircraft reached the east coast of Peninsular Malaysia. Shortly afterwards, near the border, between Malaysia and Vietnamese air traffic control the aircraft's transponder was switched off.

3. Wide of news conference ++MUTE++

4. SOUNDBITE (English) Najib Razak, Malaysian Prime Minister:

"From this point onwards the Royal Malaysian Air Force's 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 Peninsular Malaysia before turning north west. Up until the point at which it left military primary radar coverage, these movements are consistent with deliberate action by someone on the plane."

5. Photographers ++MUTE++

6. SOUNDBITE (English) Najib Razak, Malaysian Prime Minister:

"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 path."

7. Photographers ++MUTE++

8. SOUNDBITE (English) Najib Razak, Malaysian Prime Minister:

"Based on this new data the aviation authorities of Malaysia and their international counterparts have determined that the plane's last communication with a satellite was in one of two possible corridors. A northern corridor stretching approximately from the border of Kazakhstan and Turkmenistan to northern Thailand. Or a southern corridor stretching approximately from Indonesia to (the) southern Indian Ocean. The investigation team is working to further refine the information."

9. Wide of news conference ++MUTE++

10. SOUNDBITE (English) Najib Razak, Malaysian Prime Minister:

"In view of this latest development the Malaysian authorities have refocused their investigation into the crew and passengers on board."

11. Wide of news conference ++MUTE++

12. Prime minister leaving news conference.

The Malaysian jetliner missing for more than a week had its communications deliberately disabled and its last signal came about seven and a half hour after takeoff, meaning it could have ended up as far as Kazakhstan or deep in the southern Indian Ocean, Malaysia's leader said on Saturday.

Prime Minister Najib Razak's statement confirmed days of mounting speculation that the disappearance of the Malaysia Airlines Boeing 777 was not accidental, and underlined the massive task for searchers who have been scouring vast areas of ocean.

"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 path," Najib said.

"In view of this latest development, the Malaysian authorities have refocused their investigation into the crew and passengers on board," Najib added, stressing they were still investigating all possibilities as to why the plane deviated so drastically from its original flight path.

The plane was carrying 239 people when it departed for an overnight flight from Kuala Lumpur to Beijing at 00:40 local time, on March 8 (16:40 GMT on March 7).

The plane's communications with civilian air controllers were severed at about 01:20 local time (17:30 GMT), and the jet went missing in one of the most puzzling mysteries in modern aviation history.

Najib said investigators now had a high degree of certainly that one of the plane's communications systems - the Aircraft and Communications Addressing and Reporting System - was disabled before the aircraft reached the east coast of Malaysia.

Shortly afterwards, someone on board then switched off the aircraft's transponder, which communicates with civilian air traffic controllers.

The prime minister then confirmed that Malaysian air force defence radar picked up traces of the plane turning back westwards, crossing over Peninsular Malaysia into the northern stretches of the Strait of Malacca.

Authorities had previously said this radar data could not be verified.

He then said the last confirmed signal between the plane and a satellite came at 08:11 local time, 7 hours and 31 minutes after takeoff.

Airline officials have said the plane had enough fuel to fly for up to about eight hours.

Najib said authorities had determined that the plane's last communication with a satellite was in one of two possible "corridors" - a northern one from northern Thailand through to the border of Kazakhstan and Turkmenistan, and a southern one from Indonesia to the southern Indian Ocean.

He said that searching in the South China Sea, where the plane first lost contact with air traffic controllers, would be ended.

The current search involves 14 countries, 43 ships and 58 aircraft.