Storms hamper rescue efforts as 600 passengers are feared lost.
However, Aiptu Pitoyo Adi, a Rembang police official told Reuters that while fishermen who found the 66 assumed they were dead, some might be still alive but unconscious.
That left the death toll uncertain, but survivors at 177.
Rough seas with waves five to six metres high were hampering search-and-rescue efforts with only larger navy ships able to go out, as two other ships were forced to turn back.
Bustam later told ElShinta radio that the ship was built in 1990 and serviced earlier this year, “so it should not have had any problems”.
The boat was heading to Semarang in Central Java where
The Senopati Nusantara (Archipelago Commander) had been due in Semarang late on Friday after what should have been a 19-hour voyage.
Navy ships and helicopters earlier found some of the survivors stranded on the nearby island of Bawean, but could not find any trace of the ship, ElShinta radio said.
An airforce C-235 patrol aircraft was also searching for survivors.
|“I was flushed out by water and I saw many people struggling to save themselves“ A survivor|
One survivor told Reuters the ship had started to roll over after struggling in high seas and heavy rains.
“Suddenly the lights went off and it became dark. The ship’s crew tossed life jackets … some could not get any but I got one,” said Waluyo, 53.
“I tried to get into a rubber boat but many people also did the same thing, so the rubber boat was torn. Finally, I grabbed the edge of another rubber boat.”
Waluyo said he did not know the fate of his children, one a young adult and the other an infant, travelling with him.
Another survivor told Metro TV: “The crew told us to be calm and that nothing was going to happen. But at about 11:15 pm the ship began to turn over and then capsized.
“I was flushed out by water and I saw many people struggling to save themselves.”
Hatta Rajasa, the transportation minister, said the Japanese-made 2,178-tonne Senopati Nusantara was seaworthy and had a capacity of more than 850 passengers.
The ferry left Kumai in Central Kalimantan province on Borneo island en route to Semarang in central Java 420km away, and sank near Mandalika island off the Java coast.
It was not known exactly where it went down.