The MV Asia South Korea sank before dawn on Thursday in the central Phlippines, triggering a huge rescue operation involving the navy, the air force, merchant vessels and scores of fishing boats.
Civil Defence official Angel Gaviola said 614 people had been rescued and 38 were still missing. He said six people were killed but the military had put the death toll on Thursday at nine.
Gaviola said more survivors could still be found even though it was more than 24 hours since the accident.
"I think there are a lot of possibilities (of finding more survivors)," he said by telephone from Cebu, in the central Philippines.
"We heard that some survivors boarded fishing boats because that is a fishing ground area."
Rescue operations resumed at dawn after being halted at night because of bad weather, Gaviola said, adding that fishing boats, naval vessels and merchant ships were still scouring the area.
The MV Asia South Korea, carrying 606 passengers and 52 crew from Cebu to Iloilo, sank off Bantayan Island, 500 km (300 miles) southeast of Manila, at 5 a.m. on Thursday (2100 GMT Wednesday) after being buffeted by high waves.
It was the latest in a string of maritime disasters in the Philippines, an archipelagic nation of over 7,000 islands where sea transport is widely used.
In 1987, some 4,300 people were killed when a ferry collided with an oil tanker near Manila in the world's worst peacetime sea disaster.
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