Nov. 22 (Bloomberg) -- Rescue workers have picked up 243 survivors and recovered 25 bodies from an Indonesian ferry that sank off Sumatra island in rough weather today, officials said.

The Dumai Express 10, with a capacity of 270 passengers, sank on its way from Batam island to Dumai in Sumatra for unknown reasons, Bambang Ervan, a transport ministry spokesman, said by phone. The boat was carrying at least 268 people.

“The weather makes the search difficult because of the wind,” said Budi Cahyadi, head of operations at the local search and rescue office. “Waves are four to five meters.”

Rescuers, including some fishermen, found the survivors scattered over a wide area, Cahyadi said.

Officials have had difficulty establishing the exact number of passengers as not everyone was registered on the ship’s manifest, Doli Boniara, head of the local administration’s security force, said.

“We found among the survivors people who didn’t have tickets and some families were searching for their relatives whose names aren’t on the manifest,” Boniara said. “The number of victims will likely rise.”

Ferries are a much-used means of transportation for the 230 million people of Indonesia, the world’s largest archipelago nation. Weak enforcement of safety standards has led to frequent accidents.

Twenty-one people died when an overcrowded riverboat sank on the Indonesian side of Borneo island in August. There were 114 survivors.

To contact the reporter on this story: Berni Moestafa in Jakarta at bmoestafa@bloomberg.net

Last Updated: November 22, 2009 08:39 EST