An air search in the southern Indian Ocean for possible objects from the missing Malaysia Airlines plane described as the "best lead" so far ended for the day without success Thursday but will resume in the morning, Australian rescue officials said.
The four planes were checking to see if two large objects spotted in satellite imagery bobbing in the remote ocean were debris from Fight 370 that disappeared March 8 with 239 people on board.
One of the objects was 24 metres in length and the other was 5 metres. There could be other objects in the area, a four-hour flight from Australia's southwestern coast, said John Young, manager of the Australian Maritime Safety Authority's emergency response division.
"This is a lead, it's probably the best lead we have right now," Young said. He cautioned that the objects could be seaborne debris along a shipping route where containers can fall off cargo vessels, although the larger object is longer than a container.
A statement from the authority said the four planes searched an area of 23,000 square kilometres about 2,500 kilometres southwest of Perth on Thursday without success.
"The search will continue on Friday," it said.
News that possible plane parts had been found marked a new phase in the emotional roller coaster for distraught relatives of the passengers, who have criticized Malaysia harshly for not releasing timely information about the plane. While they still hope their loved ones will somehow be found, they acknowledged that news of the possible debris could mean the plane plunged into the ocean.
"If it turns out that it is truly MH370 then we will accept that fate," said Selamat Bin Omar, the father of a Malaysian passenger on the jet, which carried mostly Chinese and Malaysian nationals.
But he cautioned that relatives still "do not yet know for sure whether this is indeed MH370 or something else. Therefore we are still waiting for further notice from the Australian government."
Malaysian Defence Minister Hishammuddin Hussein told a news conference Thursday that "for all the families around the world, the one piece of information that they want most is the information we just don't have -- the location of MH370."
Young said the depth of the ocean in the latest area, which is south from where the search had been focused since Monday, is several thousand metres.
The area where the debris was spotted is about halfway between Australia and desolate islands off the Antarctic.
Flight 370 disappeared on a night flight from Kuala Lumpur to Beijing. Malaysian authorities have not ruled out any possible explanation, but have said the evidence so far suggests the plane was deliberately turned back across Malaysia to the Strait of Malacca, with its communications systems disabled. They are unsure what happened next.
Police are considering the possibility of hijacking, sabotage, terrorism or issues related to the mental health of the pilots or anyone else on board.