Kuala Lumpur: The missing Malaysia Airlines plane flew for one hour and 10 minutes after Malaysian aviation authorities saw it vanish from radar over the South China Sea and travelled hundreds of kilometres off course, according to a senior Malaysian air force official quoted by CNN.

According to the official, who had asked not to be named, the plane flew in the opposite direction from its scheduled flight path from Kuala Lumpur to Beijing with its communications equipment turned off and was last seen over a tiny island called Pulau Perak in the Strait of Malacca.

Why the pilot would be travelling in the wrong direction deepens the mystery about the fate of the plane but raises the possibility of a hijacking or technical fault that caused the pilots to not know what direction they were flying.

Later Malaysia's air force chief General Rodzali Daud denied those remarks, which had been attributed to him initially by Malaysian media.

Authorities decided to further widen the search for the plane with 239 people on board on Wednesday to cover the Andaman Sea, after intensive searches of Strait of Malacca, one of the world’s busiest shipping channels, found no sign of wreckage.

Planes and ships from 10 countries are also returning to areas in the South China Sea and Gulf of Thailand in case debris was missed in earlier searches.

The widening of the search to several hundred kilometres for the third time comes as officials in Kuala Lumpur admit they are deeply frustrated by the failure to find the plane after one of the most extensive searches ever mounted in South-East Asia.

There is also speculation the plane exploded mid-air with debris spread over a wide area.

Experts say it would take a large bomb smuggled into the cargo hold or a catastrophic technical failure to cause an explosion that would destroy the plane.

Police are investigating the possibility of a hijacking or sabotage and are delving into the psychological and personal backgrounds of all those on board.

The pilots did not radio any distress call or advise authorities they were turning back towards the coast.

Amdan Kurish, head of Malaysia’s Maritime Enforcement Agency, admitted growing frustration over the search.

“It is frustrating when we have no inkling of what happened to the plane. We are following up every possible lead 24 hours a day,” he said.

The search involves 34 aircraft and 40 ships.

Jaffar Lamri, a former Malaysian Maritime Search and Rescue Department head told the New Straits Times the plane could be lying on the bottom of the sea with choppy sea and underwater currents making it difficult to find.

“Some parts of the South China sea can be 250 metres deep,” he said.

Scott Hamilton, managing director of aviation consultancy Leeham Co, said that assuming the plane had a “impact” crash it would have been destroyed.

“Hitting the water is like hitting a brick wall. There is always some debris on the surface, which is carried away by currents and winds, making search operations even more difficult to pinpoint the actual location of impact,” he told The Star newspaper.

During four days searchers have reported numerous possible sightings of debris and oil slicks but none so far have been proven to be from the plane.

AP