Updated

South Korean officials expressed fear Tuesday of a huge death toll after rescuers failed to find any of the more than 50 fishermen missing after their ship sank amid high waves in the freezing waters of the western Bering Sea on Monday.

Authorities rescued seven crew members and recovered one body, but weather and water conditions complicated the search for the others, an official from the South Korean fisheries and oceans ministry said on condition of anonymity because of office rules.

The crew included 35 Indonesians, 13 Filipinos, 11 South Koreans and one Russian inspector, the official said. Russian authorities said there were 62 people aboard the ship, which sank in the western part of the Bering Sea, near Russia.

The South Korean ministry official said it's believed that the ship, which was catching pollock, began to list after stormy weather caused seawater to flood its storage areas. Kim Kang-ho from Sajo Industries, the canned tuna company that owns the ship, said the 2,000-ton vessel was 36 years old.

An official from South Korea's foreign ministry, who refused to be named citing office rules, said Tuesday morning that the death toll was expected to rise because rescuers failed to find any of the missing passengers. Four fishing ships that were operating nearby continue to search for survivors, but harsh weather conditions have limited their mobility, the official said.

South Korean Prime Minister Chung Hong-won vowed told a Cabinet meeting that the government will work with Russia to speed up the rescue efforts.

Authorities in the Russian port of Petropavlovsk-Kamchatsky said the rescued fishermen were well and would be taken to South Korea once the weather improves.

"The condition of the fishermen who were rescued is fine," Artur Rets, chief of the rescue center at the Petropavlovsk-Kamchatsky port, told the RIA Novosti news agency.

Kim from Sajo said the ship left for the Bering Sea from Busan, South Korea, on July 10 for the Bering Sea to catch pollock, a winter delicacy in South Korea.

Another official from Sajo, who did not want to be named, said the ship had eight lifeboats and that the seven fishermen who survived and the person later found dead used one of them to escape. The captain of the ship had issued an escape order and it was believed that the rest of the crew also attempted to escape, he said.

At the time of the sinking, the waves were more than 4 meters (13 feet) high and the water temperatures were below minus-10 degrees Celsius (14 degrees Fahrenheit), he said.

Russia allows South Korean fishermen to fish in its waters for pollock and other fish.

The ship's sinking comes months after South Korea experienced its deadliest maritime disaster in decades. The sinking of the Sewol ferry off South Korea's southwestern coast in April left more than 300 passengers dead, mostly teenagers on a school trip. The accident caused nationwide grief and fury.

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Associated Press writer Nataliya Vasilyeva in Moscow contributed to this report.