An official from the Honolulu-based US Pacific Tsunami Warning Centre (PTWC) said that his agency had told the Indonesian government of a possible small and localised tsunami but did not yet know if the quake had triggered a tsunami.

Indonesia, the world's largest archipelago, with a population of 235 million people, is prone to seismic upheaval due to its location on the "Ring of Fire," an arc of volcanos and fault lines encircling the Pacific Basin.

Last month a magnitude 8.4 earthquake hit the same region killing 23 people and destroying thousands of building.

Thursday's quake was a the latest in a series of powerful aftershocks to hit the region.