US surveillance teams have been sent to the Indian Ocean to help search for the missing Malaysia Airlines plane, after claims emerged that it may have flown for longer than investigators had thought.
Unnamed officials said flight MH370 sent signals to satellites for up to five hours after its apparent disappearance.
However, investigators stressed that the information was not conclusive.
Rescuers have so far failed to find any trace of flight MH370, which vanished last Saturday with 239 people on board.
The plane, which was flying from Kuala Lumpur to Beijing, last made contact with air-traffic control over the South China Sea to the east of Malaysia.
The US, which is one of a number of countries helping in the search for the plane, has sent a navy destroyer and a sophisticated surveillance aircraft to the Indian Ocean, hundreds of miles west of Malaysia.
The Indian navy, air force and coast guard are also now assisting after a request for help from the Malaysian government.
Several US media reports on Thursday cited 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 1,000 miles beyond its last confirmed radar sighting.
White House spokesman Jay Carney confirmed that US teams were shifting their focus to the Indian Ocean because of “new information”, but he gave no further details.
Some 153 of the passengers on board the Malaysia Airlines plane were Chinese, and Beijing has been putting pressure on Malaysia to intensify its search.
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