Rescuers searched Monday for more than 50 people missing after a South Korean fishing ship they were working on sank amid high waves in the freezing waters of the Bering Sea, officials said. At least one person died.

Authorities rescued seven crew members and recovered one body, but weather and water conditions were complicating 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. The official said the 2,100-ton ship was 35 years old.

The South Korean foreign ministry said it asked Russian officials to work quickly to rescue the other crew members.

Rescued fishermen 'fine'

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 centre at the Petropavlovsk-Kamchatsky port, told the RIA Novosti news agency. "They are currently on the ship that rescued them. They will stay there until the weather improves and South Korea decides how to get them out of here. In the likeliest scenario, they will be picked up by a Korean vessel that is out fishing nearby."

Rets said the rescue operation was ongoing.

Kim Kang-ho from Sajo Industries, which owns the ship, said it left for the Bering Sea from a port in Busan, South Korea, on July 10. Kim said there are five South Korean-owned ships currently fishing in the Bering Sea to catch pollock, a winter delicacy in South Korea.

Another official from Sajo, who didn't 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 four metres high and the water temperatures were below –10 C, he said.

Russia allows South Korean fishermen to fish in its waters for pollock, cod, Pacific saury, squid and other fish. In a meeting in April in Seoul, the two countries agreed to set this year's quota for pollock fished in Russian waters at 40,000 tons, according to a fisheries ministry official.