Search aircraft are investigating two objects spotted by satellite floating in the southern Indian Ocean off Australia that could be debris from a Malaysian jetliner missing for 12 days with 239 people on board.
Australian officials said the objects, the largest of which measured up to 24 metres (78 ft), were around 2,500 km (1,500 miles) southwest of Perth, and appeared to be awash over water several thousand metres deep.
"I can confirm we have a new lead," Malaysian Transport Minister Hishammuddin Hussein told reporters in Kuala Lumpur, where the investigation into the missing airliner is based.Read:Malaysia says satellite images credible lead, relatives stick to hope
AMSA handout of Object 1 possibly connected with MH370 search
AMSA handout of Object 2 possibly connected with MH370 search
Another official in Malaysia said investigators were "hopeful but cautious" about the Australian discovery.
No confirmed wreckage from Malaysia Airlines Flight MH370 has been found since it vanished from air traffic control screens off Malaysia's east coast early on March 8, less than an hour after taking off from Kuala Lumpur for Beijing.
"New and credible information has come to light in relation to the search for Malaysia Airlines Flight MH370 in the southern Indian Ocean," Australian Prime Minister Tony Abbott told the country's parliament.
"The Australian Maritime Safety Authority (AMSA) has received information based on satellite imagery of objects possibly related to the search."
John Young, general manager of the emergency response division of AMSA, told reporters that an Australian air force AP-3C Orion plane was already at the scene, and more aircraft were on the way. A merchant ship diverted for the task was due to arrive in a few hours, he said.
Read : Seven leading theories
Australian Maritime Safety Authority official John Young giving a press conference
"They are objects of a reasonable size and probably awash with water moving up and down over the surface," he said.
Young said it could be some days before authorities have anything to report and added that poor visibility reported in the area could hamper the search.
"It's probably the best lead we have right now but we have to get there, find them, see them, assess them, to know whether it's really meaningful or not," he said.
Prime Minister Abbott said he had already spoken with his Malaysian counterpart Najib Razak and cautioned that the objects had yet to be identified.
"The task of locating these objects will be extremely difficult and it may turn out they are not related to the search for MH370," Abbott said.
5 planes, 2 ships search southern seas for jet
5 planes, 2 ships search southern seas for jet
Four search planes and one transport plane from three countries have been sent to the site. Young said visibility was poor, which would hamper efforts. AMSA said clouds and rains obscured the view for at least one of its flights Thursday.
The search area is also far from land, so search coordinators have taken the approach of staggering the arrival of the planes.
Two Australian P-3 Orions and a New Zealand Orion were making eight-hour round trips, allowing them only two hours to search before they must return and refuel.
Made by Lockheed Martin, the Orion was once used as a submarine finder but these days is more often used for maritime patrol. They were used to help in Hurricane Katrina and the BP Horizon oil rig disaster. Their sensors can detect objects at or below the water's surface.
The U.S. Navy sent a P-8 Poseidon airplane. It is adapted from a Boeing 737 commercial jet and is designed for long-range anti-submarine warfare as well as reconnaissance.
Australia's Air Force has also sent a C-130 Hercules, a military transport plane built by Lockheed. The purpose of the Hercules is to drop marker buoys in the area.
A merchant ship that responded Monday to a request for help in the search was expected to arrive Thursday evening at the site.
The Australian Navy has sent its own ship, the HMAS Success. The Success is the largest ship built for the navy and is large enough to recover any plane debris from the ocean if needed and transport it back. The naval ship is several days from the location.
Launched in 1984, the Success is 157 meters (515 feet) long with a displacement of 18,000 metric tons. It has a crew of 220 and comes complete with its own bakery and medical operating theater.
The Hercules transport plane will drop marker buoys that float and drift with sea currents, theoretically mimicking the drift of any debris. Searchers then can track the buoys, which will be crucial if weather or other factors delay the search.
Marosszéky said the satellite images were cause for some hope in the search effort.
"But you've got to be careful," he said. "The ocean is full of debris."
FBI HELPING PROBE
AMSA handout of search area
Investigators believe that someone with detailed knowledge of both the Boeing 777-200ER and commercial aviation navigation switched off the plane's communications systems before diverting it thousands of miles off its scheduled course.
Exhaustive background checks of the passengers and crew aboard have not yielded anything that might explain why.
Investigators piecing together patchy data from military radar and satellites believe that, minutes after its identifying transponder was switched off, the plane turned sharply west, re-crossing the Malay Peninsula and following an established commercial route towards India.
After that, ephemeral pings picked up by one commercial satellite suggest the aircraft flew on for at least six hours.
The methodical shutdown of the communications systems, together with the fact that the plane appeared to be following a planned course after turning back, has focused particular attention on the pilot and co-pilot.
The FBI is helping Malaysian authorities analyse data from a flight simulator belonging to the captain of the missing plane, after initial examination showed some data logs had been deleted early last month.
A Malaysian official with knowledge of the investigations into the pilots said three simulator games that 53-year-old pilot, Zaharie Ahmad Shah, had played were being looked at.
"We are following up on the data logs being erased," the source said. "These could be logs of the games that were erased to free up memory, so it may not lead us to anything. He played a lot of games, going into hundreds and thousands of hours."
An unprecedented multinational search for the plane has focused on two vast search corridors: one arcing north overland from Laos towards the Caspian Sea, the other curving south across the Indian Ocean from west of Indonesia's Sumatra island to west of Australia.
Australia is leading the search in the southern part of the southern corridor, with assistance from the US Navy.
The depth of the water where the possible debris has been sighted would likely make recovering the "black box" voice and data recorders that may finally unlock the mystery of what happened aboard Flight MH370 extremely challenging.
Full coverage: Malaysian Airline Flight MH370