Kuala Lumpur: Investigators have concluded that one or more people with significant flying experience hijacked the missing Malaysia Airlines jet, switched off communication devices and steered it off-course, a Malaysian government official involved in the investigation said today.

No motive has been established and no demands have been made known, and it is not yet clear where the plane was taken, said the official, who spoke on condition of anonymity because he was not authorized to brief the media. The official said that hijacking was no longer a theory. "It is conclusive," he said.