There are concerns for the safety of scores of people after a ship carrying 118 passengers and crew lost power in rough waters off an Indonesian island on Saturday.

Rescuers have so far pulled at least 39 survivors from the sea, but also found three dead, authorities said.

Local search and rescue head Roki Asikin said four of the survivors were found clinging to fishing buoys in the open sea about 15 nautical miles from the mainland.

“These waves are very high,” he said. “It took three hours to evacuate to the mainland.”

They told authorities that their fibreglass boat sank hours after being hit by high waves.

One local report said the ship had left Kolaka in the Southeast Sulawesi province on Saturday bound for an unspecified destination in South Sulawesi, which lies across the Gulf of Boni.

The reported sinking is the second maritime incident in Indonesia this week. On Wednesday a cargo ship collided with a chemical tanker and sank off western Indonesia.

Six Filipino crewmen remain missing and are feared dead after the incident off Batam island, while six people were rescued.

The collision with the chemical tanker, Stolt Commitment, ripped a large hole in the Danish cargo ship, Thorco Cloud, which caused it to sink.