CANBERRA - Australia said Thursday that two objects including one estimated at 24 metres (79 feet) long had been spotted in the Indian Ocean, in the "best lead we have" in the search for a missing Malaysian passenger jet.
Australian Prime Minister Tony Abbott first broke the news to parliament, saying "new and credible information" based on satellite imagery had come to light, but stressed that the link with flight MH370 had still to be confirmed.
"Following specialist analysis of this satellite imagery, two possible objects related to the search have been identified," Abbott said.
Four long-range surveillance planes have been diverted to look into the find in the southern Indian Ocean, about 2,500 kilometres (1,553 miles) southwest of Perth.
The Malaysia Airlines Boeing 777, carrying 227 passengers and 12 crew, vanished in the early hours of March 8 after veering drastically off course over the South China Sea while en route to Beijing.
Australian Maritime Safety Authority (AMSA) official John Young said the largest object sighted "was assessed as being 24 metres. There is another one that is smaller than that."
"The objects are relatively indistinct. The indication to me is of objects that are of a reasonable size and probably awash with water and bobbing up and down over the surface," Young said.
"But we need to get there, find them, see them, assess them, to know whether it's really meaningful or not."
A merchant ship was expected to arrive in the vicinity around 0700 GMT and the Australian naval vessel HMAS Success, which is capable of retrieving any debris, is some days away.
AMSA had earlier said it had "significantly refined" the vast area of the Indian Ocean that Australia was searching, following an analysis of the jet's fuel reserves.
Sketchy radar and satellite data had initially resulted in investigators proposing two vast search corridors, stretching south into the Indian Ocean and north over South and Central Asia.
Most analysts had favoured the southern corridor, pointing out the unlikelihood of the airliner passing undetected over the nearly one dozen countries in the northern arc.
The international search has been marked by numerous false leads, and Abbott sought to temper expectations.
"We must keep in mind the task of locating these objects will be extremely difficult and it may turn out that they are not related to the search for flight MH370," he said.
'My son is still alive'
While saying "every lead is a hope," Malaysian Defence and Transport Minister Hishammuddin Hussein also stressed the need for verification.
"We want to verify, we want to corroborate," he told reporters at Kuala Lumpur International Airport.
Malaysian authorities have been criticised for their handling of the investigation, especially by relatives of those on board.
Nearly two-thirds of the passengers were Chinese, and families have gathered at the Lido Hotel in in Beijing to wait anxiously for updates.
Despite the announcement from Australia, many refused to accept that all hope was lost.
"My son is still alive. My son is still alive. I don't believe the news," cried Wen Wancheng, 63, as he pushed his way through a throng of reporters outside the relatives' room.
"We are waiting, just waiting and we can't respond to news until it is definitely confirmed," said another relative, 43-year-old Zhao Chunzeng from Beijing.
China is paying "great attention" to the news from Australia, Beijing's foreign ministry spokesman Hong Lei said in a statement.
"The Chinese side is ready to make relevant arrangements based on the latest updates," he added, without elaborating.
In Malaysia, there were chaotic, emotional scenes Wednesday when a group of tearful Chinese relatives tried to gatecrash the government's tightly controlled daily media briefing at a hotel near Kuala Lumpur airport.
Shouting and crying, the relatives unfurled a protest banner reading "Give us back our families", and accused the Malaysian authorities of withholding information.
If the plane is found in the ocean, fundamental questions will remain as to what caused it to crash.
A US official who spoke to AFP on condition of anonymity said Malaysia had asked the FBI to help recover data deleted from a flight simulator belonging to the missing plane's chief pilot, Captain Zaharie Ahmad Shah.
Malaysian police removed the simulator from Zaharie's home on Saturday, after investigators said they believed the plane had been deliberately diverted from its intended route by someone on board.
Zaharie, a 33-year veteran of the airline, was highly regarded by his peers. But suspicion has clouded him since investigators concluded the plane's communication systems were likely disabled manually and the aircraft diverted by a skilled aviator.
In his first on-camera comments on the mystery, US President Barack Obama, who is due to visit Malaysia next month, said he wanted anguished relatives to know Washington considers solving the riddle a "top priority".
Three US nationals, including an infant, were aboard.
Security was strengthened Thursday at the Kuala Lumpur airport hotel where the protest by angry Chinese relatives played out in front of the international media.
Several police officers guarded the hotel's entrance and new barriers were erected restricting access.
One hotel official told AFP that police had briefed hotel security on preventing "suspicious people" from entering.
Wednesday's ugly scenes of screaming women being forcibly carried from the briefing room only compounded the pressure on Malaysian authorities, who argue they are doing everything possible to resolve one of the biggest mysteries in aviation history.