SEOUL, South Korea - A fishing boat of the Republic of Korea (ROK) sank in frigid waters off Antarctica, killing five sailors and touching off a frantic search Monday for 17 others who were missing and feared dead, officials said.

The South Korean deep-sea fishing vessel "No 1 In Sung" which sank near Antarctica is shown in this undated photo released by Yonhap news agency December 13, 2010.  [Photo/Agencies]

Twenty survivors were rescued shortly after the 614-ton vessel went down some 1,400 miles (2,250 kilometers) south of New Zealand, ROK's Foreign Ministry and coast guard said.

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Any others in the water would be dead in 10 minutes without special suits or lifejackets, though nearby fishing boats launched a frantic search in hopes that some may have made it into a life raft, New Zealand's search and rescue center said.

"We were fortunate that there were a number of vessels in the general area (where the boat sank), so they were able to provide assistance," said Ross Henderson, a spokesman for the center. "Obviously, now, we're trying to determine the status of those 17 missing as quickly as possible."

Fishing boats from New Zealand and ROK had joined the search, according to Maritime New Zealand.

As hours passed, ROK's coast guard officer Ji Kwan-tae said it was difficult to expect the missing sailors to be alive because of the ocean's freezing temperature. Ji said he had no information on whether the missing sailors were wearing lifejackets or aboard lifeboats.

ROK owned and operated No.1 In Sung fishing boat had 42 on board when it sunk: eight South Koreans, eight Chinese, 11 Indonesians, 11 Vietnamese, three Filipinos and one Russian, ROK's Foreign Ministry said in a statement.

The confirmed dead included two Indonesians, two South Koreans and one Vietnamese, a ministry official said, speaking on condition of anonymity because of office rules.

The Chinese Embassy in ROK said four Chinese sailors were missing while four others were rescued, China's official Xinhua News Agency reported.

New Zealand's search and rescue coordination center said the 20 survivors and bodies of the five dead were on board the ROK fishing vessel No. 707 Hongjin.

Officials hoped missing crew members were able to get into a life raft or had some other survival equipment, Henderson told New Zealand's National Radio.

"Given the conditions, we're searching as quickly as we can" to locate the missing fishermen, he said.

Survival times in the water in the area would likely be about 10 minutes without lifejackets or immersion suits, the center said in a statement.

It was unclear why the vessel sank in light winds and a relatively mild 3-foot (1-meter) swell.

Separately, ROK media outlets reported that high waves that later developed in the area were hampering the rescue operation.

Officials at the South Korean-based company that owns the boat had no immediate comment.