UPDATE: Australia says a plane has spotted multiple "objects" in the Indian Ocean. A ship is expected to reach the area on Saturday.
The Malaysia Airlines flight MH370 was travelling at a much faster speed than previously thought, and search teams must now race to a different area, 1,100km northeast of the original location in the Indian Ocean.
Malaysia's Transport minister Hishammuddin Hussein told reporters on Friday that authorities are now looking at the "possibility of deep sea surveillance".
It is a race against time, authorities have warned, because soon the battery in the plane's black box will die.
The Australian Maritime Safety Authority said search teams are probing a "credible new lead" from new radar data in a different area of the Indian Ocean, in their hunt for the missing Malaysia Airlines plane, which disappeared almost three weeks ago, without a trace.
The new search area, though it is smaller than the last "remains considerable", the minister said. The advantage is how much closer the new area is to Australia, allowing planes more time to search, he added.
John Young, manager of Amsa's emergency response division, said the new information meant the search area had been refined and had now moved on from where satellite images earlier this week suggested there was debris in the ocean.
He dismissed questions suggesting that earlier searches had been a wasted effort, saying: "This is the normal business of search and rescue operations - that new information comes to light, refined analyses take you to a different place."
In a statement, Amsa said: "The Australian Transport Safety Bureau (ATSB), Australia's investigation agency, has examined this advice and determined that this is the most credible lead to where debris may be located."
"It indicated that the aircraft was traveling faster than previously estimated, resulting in increased fuel usage and reducing the possible distance the aircraft traveled south into the Indian Ocean," a statement from the AMSA said.
MH370, which was en route to Beijing from Kuala Lumpur, disappeared on March 8 with 239 people on board.
Japan and Thailand have both reported having sent new satellite images to Malaysia of potential debris fields. A French satellite has also identified 122 objects which could potentially be from the missing plane, earlier this week
The Thai images show around 300 objects, some up to 15 metres long, floating 125 miles from the spot where the French satellite found the floating objects on Wednesday.
The Japanese satellite images, taken Wednesday, show only around 10 objects, floating 1,550 miles from the western Australian coastline.
The Australian Geospatial-Intelligence Organisation is re-directing satellites to capture images of the new area.
Five Chinese ships are on their way to the new site, and Australia's HMAS Success is expected to arrive there late tomorrow night, local time.
Weather conditions in the area have improved recently. Four aircraft are already over the search area, with six more to fly over it later, including planes from Australia, Japan, Korea, New Zealand, China and the United States.
A US-towed pinger locator and a robotic underwater vehicle have also been brought to Perth to help with locating and recovering the aeroplane's black box.
In a statement on its website, Malaysia Airlines chief executive Ahmad Jauhari Yahya reiterated the company's sorrow at the loss of the plane.
He said: "The well-being and feelings of family members are and have always been close to our hearts and minds.
"Ever since the disappearance of Flight MH370, Malaysia Airlines' focus has been to comfort and support the families of those involved and support the multi-national search effort. We will continue to do this, while we also continue to support the work of the investigating authorities."
Ahmad Jauhari added that Malaysia Airlines would make arrangements to take family members to Perth if wreckage was found.
Meanwhile, the torturous wait for information continues for families of the victims. American Sarah Bajc - whose partner Philip Wood was among passengers on the flight - said regular changes in approach were "too heartbreaking" and said there needed to be a more Sherlock Holmes-style methodical investigation.
"I've stopped listening to the news. It is too heart breaking - there are so many false leads and then they change their minds and they do something else," she told BBC Radio 4's Today.