Buol, Indonesia – Six people were killed and some 10,000 displaced by the powerful 7.5-magnitude earthquake which struck Indonesia's Sulawesi island this week, officials said Tuesday.

Two more bodies were pulled from the rubble Tuesday, adding to the four already reported dead in Monday's quake which triggered tsunami warnings and sent thousands of people fleeing to higher ground, they said.

"We've recorded six people killed in the quake and some 158 people injured," Health Ministry crisis centre head Rustam Pakaya said. "Those who lost their homes have to live in tents but most people in the affected areas feel calmer now."

The district chief in the worst-hit area of Buol, Central Sulawesi, told AFP that about 1,120 houses had been flattened.

The shallow quake struck in the middle of the night off the coastal town of Gorontalo. Authorities immediately warned it was strong enough to cause a tsunami but no wave materialised.

Indonesia was the country worst hit by the earthquake-triggered tsunami in December 2004 that killed more than 200,000 people in 11 nations across Asia, including over 168,000 people in Indonesia's Aceh province alone.

The Indonesian archipelago straddles several continental plates in an area known as the Pacific Ring of Fire, where seismic and volcanic activity is recorded on an almost daily basis.