Jakarta - Rescue workers on Thursday picked up four bodies from a passenger ferry that sank four days ago in seas off the Indonesian province of West Sulawesi, raising fears that more than 200 other missing people have died as well, officials said.

"We have just got reports that rescue workers recovered four bodies and now they were on board a Navy warship heading the search operation," said Junaedi, an official at western Sulawesi port town of Majene, the closest port to the ferry's location when it sank.

He said the four bodies, twos adult and two children, were recovered from seas near Laboso Bay, about 18 kilometres from where the ferry went down Sunday morning, carrying 267 people.

Junaedi, who like many Indonesians goes only by one name, said the recovery brought the number of bodies to six. Thirty-five 35 people survivedthe accident, leaving at least 226 remaining missing and believed drowned.

Many officials believe most of the missing persons were trapped inside and went down with the ferry.

Junaedi said the search was continuing, supported by seven vessels, including five warships, a marine patrol boat and a search and rescue vessel.

The Teratai Prima ferry sank before dawn Sunday in rough seas off the port town of Majene while en route from the port of Pare-pare on southern Sulawesi to Samarinda, East Kalimantan.

The harbour master in Pare-pare said based on the manifest, the ferry was carrying 250 passengers and 17 crew members.

But local media quoted relatives of those missing as saying that more than 100 names of peopled believed to have travelled on the ferry were not on the manifest.

President Susilo Bambang Yudhoyono on Wednesday ordered a thorough investigation into the ferry disaster, known as the worst marine accident in Indonesia this year.

Frequent maritime accidents claim hundreds of lives every year in Indonesia, largely due to poor enforcement of safety regulations and overcrowding. Indonesia, an archipelago of more than 17,000 islands, depends heavily on ocean transport.

In December 2006, a ship with 638 people aboard sank off East Java province. Only 230 people survived. (dpa)