The death toll from a ferry boat tragedy in the remote interior of Sarawak rose to 13 today as police said that seven more bodies had been found.

Thirty people were believed to be travelling on the boat, which collided with a barge on Monday as it travelled along the upper reaches of the Anap river in central Sarawak.

Seventeen people were rescued after escaping from the wreckage, but district marine police chief Iswandi Ken said seven more bodies had been found in addition to the six recovered earlier.

"We have found the bodies of four women and three men this morning at the accident site and this brings the total number of bodies so far found in the boat accident to 13," he said.

"Search operations are still ongoing but we have accounted for all individuals reported missing so far," he said. "We are not expecting to find anyone else."

Confusion over how many people were on the vessel had hampered the rescued effort, which took place in an inaccessible jungle region.

"The police are still investigating the cause of the accident and it will be some time before we can get a proper report of what happened," Iswandi said.

Many parts of Sarawak, an underdeveloped and heavily forested state, are only accessible by air or by river.

Transport along the long waterways is popular with people travelling between inland areas and coastal towns.

- AFP