U.S. President Barack Obama has promised more help in the search for the missing Malaysia Airlines jet, while in the country on a visit.
Mr Obama said on Sunday that the US was fully committed to providing more assets to assist in the search for MH370 in the southern Indian Ocean.
"I can tell you the United States is absolutely committed to providing whatever resources and assets that we can," Obama told a news conference in Kuala Lumpur.
A US Navy submersible drone has been scanning a patch of the Indian Ocean seabed but has been unable to find any trace of the Boeing 777.
The search is as much in the interest of America as it is in Malaysia's as experts say it is essential to find out why the American-built plane could have veered so far off course.
Flight MH370 disappeared on March 8 while on route to Beijing from Kuala Lumpur, but was later traced to an area about 1,000miles (1,500km) off Australia's west coast.
More than seven weeks after the jet carrying 239 people vanished, authorities are now regrouping to decide how to proceed.
The Australia-based Joint Agency Coordination Centre, which is in charge of the search, told Reuters: "We are currently consulting very closely with our international partners on the best way to continue the search into the future."
Malaysia, China, Japan, New Zealand, South Korea, Britain and the United States are assisting Australia in the most expensive search in aviation history.
Mr Obama said: "Obviously we don't know all the details but we do know, if in fact the plane went down in the ocean on this part of this world, there is a big place and it is very challenging effort and laboriously effort.
"It is going to take quite some time."
A US defence official told Reuters on Friday that the search was likely to drag on for years.
The official said the hunt was entering a much more difficult phase, which will involve scouring broader areas of the ocean near where the plane is believed to have crashed.
Australia and Malaysia have been under pressure to bring closure to the grieving families of those on board MH370 by finding anything that may help determine what happened to the aircraft.
Malaysia is also under growing pressure to disclose more about its investigation into what happened, although Mr Obama said the country had been "fully forthcoming" in sharing information.
Mr Najib has said his government would make public a preliminary report into the plane's disappearance next week.
Until now, the undersea search has been focused on a 10 square km (6.2 square mile) zone where a series of "pings" were detected earlier this month.
This will be extended if the US Bluefin-21 underwater drone fails to find anything.
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