The airline said the public can call +60-378841234 for information about the plane.
Licensed pilot John Preston said that rumours that the aircraft has made an emergency landing in Nanming are unlikely.
"I think we can safely discount that."
He said Chinese authorities had confirmed the plane had not entered their airspace. He said there were several ways for the aircraft to communicate with the authorities but that does not appear to have happened.
China's state-run news agency Xinhua reported the plane was lost in airspace controlled by Vietnam, and did not make contact with Chinese air traffic controllers. China is assisting the airline in its search for the plane, Xinhua said.
There were no storms in the area of the South China Sea where the plane was flying across. The weather was generally fine with light clouds.
Malaysia Airlines denied reports circulating on the internet the plane had landed safely in Nanjing China.
"It's not true. We don't know where the plane is now," said Fuad Sharuji, from the airline's operation control centre.
Mr Fuad confirmed contact was lost two hours into its six-hour flight. The pilots made no distress call.
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