The missing Malaysia Airlines Flight MH370 was shot down during a joint Thai-US military training exercise and then the subject of an elaborate international cover-up, according to a book on the lost plane.

The book, "Flight MH370: The Mystery", will go on sale in Australia on Monday (May 19), just 71 days after the Boeing 777 vanished en route from Kuala Lumpur to Beijing, UK's The Independent newspaper said quoting a Sun-Herald report.

The book has been written by the Anglo-American journalist and author Nigel Cawthorne.

Cawthorne claims that the families of the passengers will "almost certainly" never be sure what happened to their loved ones.

But he goes on to support one theory, based on the eye-witness testimony of New Zealand oil rig worker Mike McKay, that the plane was shot down shortly after it stopped communicating with air traffic controllers, the report said.

At the time there was a series of war games taking place in the South China Sea involving Thailand, the US and personnel from China, Japan, Indonesia and others, and Cawthorne has linked this to McKay's claims to have seen a burning plane going down in the Gulf of Thailand.

"The drill was to involve mock warfare on land, in water and in the air, and would include live-fire exercises," Cawthorne said.

"Say a participant accidentally shot down Flight MH370. Such things do happen. No one wants another Lockerbie [Pan Am flight 103 by terrorists in 1988 allegedly in retaliation for a US Navy strike on an Iranian commercial jet six months earlier], so those involved would have every reason to keep quiet about it."

Cawthorne then suggests that "another black box" could have been dropped off the coast of Australia to divert the efforts of search teams. "After all, no wreckage has been found in the south Indian Ocean, which in itself is suspicious," he wrote.