Malaysia Airlines (MAS) has confirmed that its flight MH370 carrying 239 people has lost contact with ground air traffic control on Saturday enroute to Beijing.

Its chief executive officer Ahmad Jauhari Yahya said the airline is contacting next-of-kin of the passengers and crew.

"We deeply regret that we have lost all contacts with flight MH370," he said in a statement emailed to The Straits Times.

"Focus of the airline is to work with the emergency responders and authorities and mobilize its full support."

MAS said earlier that the Boeing B777-200 aircraft left Kuala Lumpur at 12.41am on Saturday and had been expected to land in Beijing at 6.30am the same day.

But it lost contact with Subang Air Traffic Control at 2.40am on Saturday.

The flight was carrying 227 passengers, including two infants, and 12 crew members.

According to Xinhua news agency, there are 160 passengers from China.

It said contact was lost with the plane while it was over Vietnamese airspace.

Xinhua also quoted Chinese aviation authorities saying the plane did not enter China's air traffic control sphere.