US officials helping with the search for Flight MH370 are “shifting focus” to the “Indian Ocean region”.
However, one official told the BBC that this did not necessary mean specific new leads.
White House spokesman Jay Carney said fresh lines of investigation were the reason why the scope had widened.
The plane went missing early on Saturday with 239 people on board. A search over a massive area has failed to find any clue to its disappearance.
White House spokesman Jay Carney told reporters that “because of new information, we may be part of an effort to open a new search area in the Indian Ocean,” and that the US was consulting with the Malaysian government on what resources might be deployed.
However, officials told the BBC the intelligence was “not concrete enough to merit a rise in expectations”.
The US Navy has also announced it is moving a destroyer, the USS Kidd, from its search position in the Gulf of Thailand, to the west coast of Malaysia.
Meanwhile, the Indian Navy, Air Force and coast guard are also now assisting, after a request for help from the Malaysian government.
In an echo of claims made in the Wall Street Journal earlier on Thursday that the plane transmitted engine data for hours after the plane disappeared, US officials briefed on the search told Associated Press that Boeing systems on the plane also sent signals to a satellite for four hours after the aircraft went missing.
The Boeing 777-200 was not transmitting data to the satellite, but was instead sending out a signal to establish contact, said the official, who was not named.
If true, it could suggest the aircraft was still flying.
Boeing offers a satellite service that can receive a stream of data during flight on how the aircraft is functioning. Malaysia Airlines did not subscribe to that service, but the plane was still automatically sending pings to the satellite, the official said.
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 official said. The plane had enough fuel to fly about four more hours, he said.
Meanwhile two American officials have told ABC news that two on-board communication systems stopped transmitting data at different times, possibly indicating that the plane did not suffer catastrophic failure.
The data reporting system, they claimed, stopped transmitting at 01:07 (17:07 GMT), while the transponder, which transmits location and altitude and identifies the plane to radar, shut down at 01:21 (17:21 GMT), they told ABC.
Earlier on Thursday, Malaysia’s acting Transport Minister Hishammuddin Hussein rejected the Wall Street Journal’s claims about engine data transmission, saying that both engine makers Rolls-Royce, and Malaysian Airlines said they were “inaccurate”.
“The last transmission from the aircraft was at 01:07 which indicated that everything was normal,” he said. The Malaysian government has yet to respond to the latest reports.
Satellite image confusion
Also on Thursday, Mr Hussain said that Chinese satellite pictures of debris in the South China Sea were not connected to Flight MH370’s disappearance.
The grainy satellite images were released by China’s State Administration of Science on Wednesday.
He said the Chinese embassy in Kuala Lumpur had told Malaysian authorities that the release of the pictures was a “mistake”.
Chinese state TV is still treating the pictures as relevant and says a warship is continuing to search for the debris in the South China Sea.
Correspondents say the general agreement in China is that Chinese search efforts are going to continue despite Malaysia’s dismissal of the satellite pictures.
Some have dismissed Malaysian efforts to find the plane, and a state media TV report has suggested Malaysia was unable to analyse China’s satellite pictures properly, correspondents say.
The plane was en route to Beijing from Kuala Lumpur and 153 Chinese were on board.
In Vietnam, an air traffic official said five ships and three aircraft had been sent on Thursday to the area indicated by the Chinese satellite images but had found nothing.