Geological experts detected an undersea earthquake measuring 6.5 on the Richter scale to the east of the island of Sulawesi in the Indonesian archipelago.

BBC's Jonathan Head: Death toll likely to rise

Dozens of houses collapsed or slid into the sea. One of the many landslides destroyed the island's main docks.

Many people fled to higher ground for fear of tsunami - commonly known as tidal waves - especially those living in coastal villages on Mangole island near the epicentre of the tremor. However, none have been reported.

There are fears the death toll could rise as rescue workers sift through the ruins of a timber factory where the roof collapsed.

Several hundred people are thought to have been working there.

The regional authorities say electricity on the island has been cut off and many roads have been damaged, making communication difficult.

Injured airlifted

Military personnel and volunteers have been putting up tents for the homeless.

Officials said urgent supplies of food and medicine were needed. The island has no major hospital.

A local government official, Karim Wamona, said emergency flights were taking seriously injured victims to neighbouring islands for urgent treatment.

"People are now gathering in a football field. There was a lot of panic. They are too afraid to sleep because there might be aftershocks," said police sergeant Yopi Sariwating by telephone.

About 38,000 people live on the island of Mangole, one of the more isolated of Indonesia's thousands of islands. Its economy is dominated by the timber industry.

Tsunami fears

The US Geological Survey said the earthquake struck on Sunday night local time, at 1410GMT.

It was more severe than the one which led to the giant wave that killed more than 2,000 people in Papua New Guinea in July.

A tsunami can occur within minutes or hours of a quake - or not at all.

Stuart Koyanagi of the US Geological Survey: "That is a major earthquake"

A spokesman for the US Geological Survey warned that people living on small Indonesian islands may be at risk.

He said the epicentre of the quake was near the island of Taliabu about 230 miles (370km) south of Manado on Sulawesi island.

In December 1992, an earthquake caused a tsunami that killed about 2,500 people on the nearby island of Flores.

Earthquakes are common in Indonesia, which lies astride the Pacific "Ring of Fire" - a line of volcanically active areas circling the Pacific basin.