Air cargo industry insiders suggest Malaysia Airlines Flight MH370 may have been carrying highly valuable cargo that may possibly be the motive for the alleged hijacking.

The claim comes as investigators reveal the Boeing 777 carrying 227 passengers and 12 crew went on a wild flight path after it changed course, climbing to 15,000m before descending to 1500m, possibly to avoid military radar.

Sources close to the investigation have told _The West Australian _they suspect MH370 may have flown at this low altitude past - and over - three countries.

According to cargo sources in Singapore, the plane was carrying cargo that was "highly valuable", though its nature has not been revealed.

Clarification is being sought from Malaysia Airlines.

The US Navy assists in search and rescue operations for Malaysia Airlines flight MH370 in the Indian Ocean. Photo: AP.

The number of nations involved in the search for the plane has risen to 25 and the search area extends from the Indian Ocean to as far north as the southern border of China.

According to Paul Hayes, director of aviation security at Ascend Worldwide, "if it's gone off into the Indian Ocean somewhere, there's a good chance you'll never find it".

"It's the first aircraft that's ever disappeared like this with no suggestion of a motive, with nobody claiming responsibility," Mr Hayes said.

"With other hijacked aircraft, you knew they were hijacked."

The plane had enough fuel for just over seven hours of flying and it changed course after about 50 minutes. But the plane would have burnt much more fuel at lower altitudes.

Malaysian police are now rechecking the background of passengers and crew.

There is renewed scrutiny of the pilots, Capt. Zaharie Ahmad Shah and First Officer Fariq Abdul Hamid, and if they were aware that the jet's Aircraft Communications and Reporting System had been cut off.

However, a Boeing 777 pilot told _The West Australian _that pilots would be unaware that it was turned off and this could be done from the underfloor main equipment bay near the forward galley.

Prime Minister Tony Abbott told Federal Parliament yesterday that he had spoken to Malaysian counterpart Najib Razak.

"He asked that Australia take responsibility for the search in the southern vector, which the Malaysian authorities now think was one possible flight path for this ill-fated aircraft," Mr Abbott said.

Mr Razak also accepted an offer of extra Australian maritime surveillance resources. The China Maritime Search and Rescue Centre has asked Chinese merchant ships in the Indian Ocean, Bay of Bengal and waters west of Australia to help.

The West Australian

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