Kuala Lumpur, Malaysia - China released a new image of a "suspected floating object" in the Indian Ocean on Saturday, in the vicinity of an Australian-led search that has brought fresh hope to the hunt for a missing Malaysia Airlines jetliner.

China has sent ships to investigate, according to the Malaysian government. But Australia said its planes had already passed over the same area on Saturday and did not find anything.

The Chinese government said one of its satellites spotted the object on March 18, about 75 miles southwest of the location released by Australia last week.

A grainy image of the latest find was tweeted Saturday by Chinese state television, CCTV. It is dated two days after the two images released by Australia.

The search for the missing airliner has now entered a third week, with the main hope for a breakthrough hinging on planes and ships being able to locate floating objects picked up by satellites in a desolate stretch of ocean almost as close to Antarctica as to Australia.

On Saturday, Malaysia's Defense Minister Hishammuddin Hussein interrupted a news conference to say he had just received "breaking news" from the Chinese ambassador, that a new satellite image had been received showing a floating object in the Indian Ocean.

"They will be sending ships to verify," he said. The object was 74 feet by 43 feet, the Malaysian government later said.

A Boeing 777-200 is 209 feet long, with a wingspan of 199 feet and a tail height of 60 feet, but its body is only 20 feet in diameter.

Piece of a wing?

Experts said a piece this large could only conceivably have come from a wing. But even if empty fuel tanks inside the wing were filled with air, some doubted it could stay afloat for 10 days after the Malaysia Airlines plane vanished on March 8, especially in rough seas.

The search for any debris from the plane is complicated by strong and unpredictable currents in this part of the Indian Ocean. The two objects spotted by satellite last Sunday that are the focus of the Australian-led search could already have drifted more than 100 miles, experts said.

Charitha Pattiaratchi, a professor of coastal oceanography at the University of Western Australia in Crawley, said currents in the area are generally moving in a northeasterly direction. He said the debris spotted by the Chinese satellite could easily have come from the same crash site as the other debris, but could be trailing behind. "The bigger it is, the harder it is to move," he said. "It is totally consistent with what we know."

For the past two days, surveillance planes have been passing back and forth over the Indian Ocean to try and locate the objects identified by Australia, without any result. The search has become a race against time - before the objects drift too far, break up or sink in heavy ocean swells, and because bad weather is expected to set in Sunday and last through next week.

On Saturday, one of the civilian planes reported seeing a "number of small objects" floating in the water within a radius of three miles, including a wooden pallet, the Australian Maritime Safety Authority (AMSA) said in a statement. But when a New Zealand air force P3 Orion plane "with specialist electro-optic observation equipment" went to the area, all it could see were clumps of seaweed.

A merchant ship has been asked to return to the area for a closer look, AMSA said. The agency, which is coordinating the search in the southern Indian Ocean, said it would also evaluate the information supplied by China and take it into account in today's search plans.

Given strong and unpredictable ocean currents, the two objects identified by Australia could already be more than 100 miles from the location where they were first spotted by satellite, experts said. The more time passes, the harder they are to find.

Three Australian P-3 Orion surveillance planes and one from New Zealand were being joined Saturday by two long-range commercial jets, with trained volunteers on board peering out of windows.

Two merchant ships were joined by an Australian naval vessel, while China said two of its air force transport planes arrived in Perth from Malaysia Saturday to assist.

Saturday's search centered on an area of roughly 14,000 square miles, lying some 1,550 miles southwest of the Australian west coast city of Perth. It partly overlapped with a smaller area searched on Friday, and with a larger patch of ocean searched on Thursday, according to maps and data supplied by the Australian Maritime Safety Authority (AMSA).

Warren Truss, Australia's deputy prime minister, said a complete search could take a long time and warned that the objects could have sunk already.

"Even though this is not a definite lead, it is probably more solid than any other lead around the world, and that is why so much effort and interest is being put into this search," he told reporters at the air force base in Perth in western Australia that is being used as a staging area for the search planes.

"It is a very remote area, but we intend to continue the search until we're absolutely satisfied that further searching would be futile - and that day is not in sight."

The area takes four hours flying time to reach, meaning the Orions only have enough fuel for two hours searching before having to return home. The commercial jets can search on site for five hours. The Australian Maritime Safety Authority said radar sweeps of the area have not turned up anything yet, meaning the effort is largely having to rely on spotters scanning vast expanses of ocean by eye.

"While these aircraft are equipped with very advanced technology, much of this search is actually visual," Truss said.

While the AMSA and pilots reported good visibility of around six miles Friday and Saturday, that may not last. Meteorologists say worse weather is expected to set in today, with a series of fronts passing through the area throughout this week.

That raises the prospect of rain, huge swells and wind-driven waves capped by white caps in a remote and inhospitable part of the Indian Ocean swept by fierce westerly winds known as the Roaring Forties.

A category one cyclone struck Australia's Christmas Island on Saturday, 1,600 miles northwest of Perth, and could bring further bad weather to the search area.

Time pressure is heightened by the fact that the location beacon built into the plane's black box is only likely to keep transmitting for another two weeks, before its batteries run out. Even if the objects spotted by satellite are found and turn out to have come from the plane, they could have drifted hundreds of miles from a possible crash site on March 8.

Complex and uncertain mathematical modeling will have to be employed to track back and find out where the plane might have come down, and naval vessels equipped with sonar technology will have to sweep the area listening for beeps from the black box.

Then, it will be a case of searching the deep ocean floor with undersea drones, roughly two miles beneath the surface, to look for the main wreckage.

When an Air France plane crashed into the Atlantic in 2009, the first debris and bodies were pulled from the sea after five days, but it took more than two years to find the main wreckage on the ocean floor. That was partly because those mathematic models of ocean currents initially sent investigators to the wrong place.

The two objects identified by Australia this week were roughly 80 feet and 15 feet long, respectively.

Peter Marosszeky, an aviation expert at the University of New South Wales, said the larger object could have been a piece of wing, kept afloat for a while by air in empty fuel tanks, or a fin - or simply a piece of unrelated debris, of the sort that litters the oceans of the world. "At the moment, it's all conjecture," he said.

Alan Kin-Tak Lau, an expert in aircraft maintenance and accidents at Hong Kong Polytechnic University, said he did not believe the large objects spotted by the Chinese or Australians were from a plane, since large metal aircraft parts would usually have sunk fairly quickly.

"The only material you would expect to see is luggage and baggage and seats," he said. "The metal parts are too heavy, and for the Boeing 777, the whole aircraft is made of aluminum."

Meanwhile, the search for the Malaysia Airlines plane is continuing in other parts of the world, both over land across vast swathes of central and southeast Asia, and over other parts of the Indian Ocean where the plane's final satellite transmissions suggested it might have been at 8:11 a.m. on the morning of March 8.

Hishammuddin said China, India, Pakistan, Myanmar, Laos, Kyrgyzstan and Kazakhstan had informed Malaysia that "preliminary analysis" had not revealed any sightings of the plane in the northern search area, primarily on land.

Malaysia Airlines Flight 370 vanished from civilian radar at 1:21 a.m. on March 8, not long after setting off from Kuala Lumpur on its way to Beijing. It then did a U-turn and headed west back across the Malaysian peninsula, before vanishing from Malaysian military radar at 2:11 a.m. in the northern end of the Strait of Malacca.

The Malaysians running the investigations say they believe the flight must have been deliberately flown off course, either by one of its pilots or by hijackers, but have not ruled some kind of catastrophic mechanic failure.

But there was no indication that the investigation into what may have caused the flight to disappear had yielded new information.

A transcript of the cockpit's last minutes of conversation with air traffic controllers "does not indicate anything abnormal," Hishammuddin said.

He did not comment on a report in the Sydney Morning Herald that nothing suspicious had been found on data taken from the flight simulator of the pilot Zaharie Ahmad Shah.