Jakarta  - Indonesian rescue workers resumed their search Monday for dozens of people missing people after an overloaded ferry sank in bad weather off the island of Sumatra, officials said.

Rescue teams had picked up about 250 survivors and 27 bodies by Monday morning, while the number of missing remains unknown.

Other officials said 29 bodies had been retrieved. Rustam Pakaya from the Health Ministry's crisis centre said at least 17 other people were still missing.

According to the ferry's manifest, the Dumai Express 10 was carrying 228 passengers, including 15 children, as well as 14 crew when it sank on Sunday on its way from Batam near Singapore to Dumai in Riau, Sumatra.

But rescue officials said many passengers, including children, were not listed on the manifest. Overcrowding is common on Indonesian ferries.

Rescue workers resumed their work with officials assuming that dozens of passengers were trapped inside the ferry which sank in about 32 metres of water, said Oktafinus, an official at Riau's port, who like many Indonesians uses only one name.

Another ferry, the Dumai Express 15, with 278 people on board, ran aground after it was hit by large waves on its way from Batam on Sunday. All passengers and crew survived, said Sunaryo, director general of sea transport.

Hundreds have in recent years been killed in ferry accidents in Indonesia. The vessels are often overcrowded, with safety regulations poorly enforced.

The vast country spans more than 17,000 islands and boats are a popular and relatively cheap form of transport. (dpa)