Malaysia plane: Flight MH370 search enters second week
A huge international operation is continuing to try to find the Malaysia Airlines flight MH370 - one week after the plane with 239 people disappeared.
Search efforts are focusing on the area to the west of the Malay Peninsula.
Information has emerged that the plane may have been flying for at least five hours after it vanished.
Investigators are working on a theory someone with flight experience took control of the plane, halted communications and changed course.
An unnamed source close to the Malaysian investigation told the Associated Press: "It is conclusive."
No one has offered any conjectures about who might have done this, or why.
Malaysian Prime Minister Najib Razak is due to give a press conference at 13:30 (05:30 GMT).
It is believed the Kuala Lumpur-Beijing flight was sending automated signals to a satellite system long after radar contact was lost, the BBC has learned.
The plane last made contact with air traffic control over the South China Sea to the east of Malaysia.
However, the BBC understands that a satellite system operated by London-based telecommunications company Inmarsat received an automated signal from flight MH370 at least five hours after the plane was reported lost.
Earlier, US media outlets also quoted unnamed officials as saying that the Boeing 777 was "pinging" satellites for hours after its last contact with air traffic controllers.
That led searchers to believe the plane could have flown more than 1,600 km (1,000 miles) beyond its last confirmed radar sighting.
The US has sent a naval ship and a surveillance plane to search areas of the Bay of Bengal, the Andaman Sea and parts of the Indian Ocean.
White House spokesman Jay Carney has confirmed that US teams were shifting their focus to the Indian Ocean because of "new information", but gave no further details.
The Indian navy, air force and coast guard are also now involved after a request from the Malaysian government.
Indian naval spokesman DK Sharma said on Friday that six ships and five aircraft were scouring the Andaman Sea.
Malaysian authorities later said that India's Eastern Naval Command was to search an area of sea 9,000 sq km (3,500 sq miles) off the Chennai coast
The BBC's Jonathan Head in Kuala Lumpur says the latest claims are being taken seriously by the US.
However, he cautions that there have already been a number of false leads.
As the search continues, families of those on board are enduring an agonising wait for news.
Feng Zhiliang, whose cousin Feng Dong, 21, was a passenger, told the BBC in Beijing that families had spent the past week "in agony and desperation".
"We are very disappointed with the response of the Malaysian authorities. The information they give out is completely contradictory."
He added: "Until it's clear what happened we still have hope that our families will return home safely."
Malaysia's acting Transport Minister Hishammuddin Hussein said that the search area was expanding both east and west of the Malaysian peninsula.
China said on Friday it was sending a patrol ship to the Malacca Strait, west of Malaysia, after a fruitless search in the Gulf in Thailand.
Some 153 of the passengers on board the plane were Chinese, and Beijing has been pressing Malaysia to intensify its search.
Earlier this week, Chinese officials released satellite pictures of debris in the South China Sea.
Mr Hussein later said the images were not connected to flight MH370's disappearance.
But Chinese state TV said a warship was continuing to search for the debris.