Marc Dugain reckons MH370 was shot down by US military Getty

Malaysia Airlines flight MH370 was blasted out of the sky by the US military over fears it had been hacked for use in a terror outrage, a top aviation figure has claimed.

According to aviation veteran Marc Dugain, the jumbo jet was shot down near a US military base on the remote island of Diego Garcia after diverting to the area following a hack of its computer systems.

Dugain speculated that military personnel on the base in the Indian Ocean feared the craft was about to be used in a 9/11-style atrocity - and so shot it down.

He claimed the plane's unexpected presence in the area might have been the result of a fire on board or a hack that had diverted it toward the British-controlled territory.

Dugain - the former chief executive of defunct Proteus Airlines - said islanders in the Maldives near to Diego Garcia had told him they saw MH370 flying at a low altitude.

A fisherman on a tiny island told him of a "huge plane... with red and blue strips on a white background" flying overhead, soon after MH370 vanished on March 8.

Also, an empty fire extinguisher from the missing plane was recovered from the waters by islanders on nearby Baarah island, claimed Dugain, speaking to Paris Match.

If true, this would undermine a popular theory that everyone on board MH370 died from oxygen starvation before it glided in to the sea.

Speaking elsewhere, Dugain told a radio station he was warned not to investigate MH370's fate by an intelligence source, who spoke of "risks" and advised him to "let time do its work".

A joint effort between Australia and Malaysia to find the plane is running behind due to equipment problems affecting the search of Indian Ocean floor.