A photo shows the scene in the cabin as the aircraft descended. 

An aircraft heading to Beijing from Bali Island was forced into a sharp descent from around 30,000 to around 10,000 feet due to a fault with the aircraft, Saturday.

China Eastern Airlines say Flight MU782 landed safely at an alternative airport in Malaysia at around 5 o'clock this morning, with everyone on the flight safe and sound.

The incident occurred about one and a half hours after the aircraft took off, and the airline says the whole process lasted for about 10 minutes.

The aircrew put contingency plans into operation immediately after the incident, reducing altitude and releasing all the oxygen masks on board.

China Eastern Airlines has already dispatched another plane to collect the passengers to avoid further delay to their onward travel plans.

The reason for the aircraft fault is still unknown.

A photo shows the scene in the cabin as the aircraft descended.