A relative of Chinese passengers aboard the missing Malaysia Airlines flight MH370 grieves alone in a corridor at a hotel in Beijing (AP)

Relatives of Chinese passengers who were on missing Malaysia Airlines flight MH370 speak to journalists at a hotel in Beijing (AP)

Children read messages displayed for all involved with the missing Malaysia Airlines plane MH370 on the walls of the Kuala Lumpur International Airport (AP)

Relatives are still waiting for news on what happened to the missing Malaysian airliner (AP Photo/Andy Wong)

Two objects may have been found in the search for the missing Malaysian jet, the Australian prime minister Tony Abott has said.

Four military search planes were dispatched to try to determine whether the large objects bobbing in a remote part of the Indian Ocean were debris from the missing Malaysia Airlines flight.

One of the objects spotted by satellite imagery had a dimension of 25 metres (82 feet) and the other one was smaller.

There could be other objects in waters nearby in the area that is a four-hour flight from Australia's coast, said John Young, manager of Australian Maritime Safety Authority's emergency response division.

"This is a lead, it's probably the best lead we have right now," he said, while cautioning that the objects could also be seaborne debris along a key shipping route where containers periodically fall off cargo vessels.

Mr Young told a news conference in Canberra, Australia's capital, that planes had been sent to the area about 1,550 miles south-west of Perth to check on the objects.

He said that satellite images "do not always turn out to be related to the search even if they look good, so we will hold our views on that until they are sighted close-up".

Australian prime minister Tony Abbott had earlier told Parliament about the debris, and said Orion search aircraft were expected to arrive in the area later today.

He said that a Royal Australian Airforce Orion has been diverted to the area to attempt to locate the objects.

The Orion is expected to arrive in the area later today. Three additional aircraft were expected to follow for a more intensive search.

Mr Abbott cautioned, however, that 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".

Mr Young said visibility was poor and may hamper efforts to find the objects.

He said they "are relatively indistinct on the imagery ... but those who are experts indicate they are credible sightings.

"The indication to me is of objects that are a reasonable size and probably awash with water, moving up and down over the surface."

He warned against expectations that this may help solve the mystery of the plane that went missing with 239 people on board.

He told reporters, "We have been in this business of doing search and rescue and using sat images before and they do not always turn out to be related to the search even if they look good, so we will hold our views on that until they are sighted close-up."

Military planes from Australia, the US and New Zealand have been covering a search region over the southern Indian Ocean that was narrowed down from 232,000 square miles to 117,000 square miles.

The hunt for the Boeing 777 has been punctuated by several false leads since it disappeared March 8 above the Gulf of Thailand.

Oil slicks that were spotted did not contain jet fuel. A yellow object thought to be from the plane turned out to be a piece of sea trash. Chinese satellite images showed possible plane debris, but nothing was found.

But this is the first time that possible objects have been spotted since the search area was massively expanded into two corridors, one stretching from northern Thailand into Central Asia and the other from the Strait of Malacca down to southern reaches of the Indian Ocean.

Australia's envoy to Malaysia, Rod Smith, joined a meeting of senior Malaysia search officials at a Kuala Lumpur hotel after Mr Abbott's announcement.

"As I've been doing from day one, I've followed every single lead. And this time, I hope it is a positive development," Malaysian defence minister Hishammuddin Hussein told reporters.

The FBI has also joined forces with Malaysian authorities in analysing deleted data on a flight simulator belonging to the pilot of the missing jet.

Files containing records of flight simulations were deleted on February 3 from the device found in the home of the pilot, Captain Zaharie Ahmad Shah, Malaysian police chief Khalid Abu said.

It was not clear whether investigators thought that deleting the files was unusual. They might hold hints of unusual flight paths that could help explain where the missing plane went, or the files could have been deleted simply to clear memory for other material.

Mr Hishammuddin told a news conference yesterday that Captain Zaharie is considered innocent until proven guilty. He said members of the pilot's family are cooperating in the investigation.

The captain was known to some within the online world of flight simulation enthusiasts.

A US official said the FBI has been asked to analyze the deleted simulator files.

US Attorney General Eric Holder said in Washington that the FBI was working with Malaysian authorities. "At this point, I don't think we have any theories," he said.

Flight 370 disappeared on March 8 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 flight was deliberately turned back across Malaysia to the Strait of Malacca, with its communications systems disabled. They are unsure what happened next.

Investigators have identified two giant arcs of territory spanning the possible positions of the plane about seven-and-a-half hours after take-off, based on its last faint signal to a satellite - an hourly "handshake" signal that continues even when communications are switched off.

The arcs stretch up as far as Kazakhstan in central Asia and down deep into the southern Indian Ocean.

Police are considering the possibility of hijacking, sabotage, terrorism or issues related to the mental health of the pilots or anyone else on board, and have asked for background checks from abroad on all foreign passengers.

But John Young of the Australian Maritime Safety Authority warned against expectations that this may help solve the mystery of the plane that went missing with 239 people on board.

He told reporters, "We have been in this business of doing search and rescue and using sat images before and they do not always turn out to be related to the search even if they look good, so we will hold our views on that until they are sighted close-up."

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