At least five sailors have been killed and 17 are missing after a South Korean deep-sea trawler with 42 crew members on board sank off Antarctica, maritime authorities have said.

"The vessel is believed to have gone down at 6.30am, about 1,000 nautical miles north of McMurdo [Antarctic base]," Ross Henderson, spokesman for Maritime New Zealand, told the AFP news agency on Monday.

"We have 20 alive, four deceased and 18 missing."

Henderson said all vessels in the remote area had been asked to steam to the site where the 614-tonne Number One Insung went down to assist the search for survivors.

A Royal New Zealand Air Force Orion plane was also being sent to the area, he said.

Henderson added that New Zealand authorities received no distress call before the ship sank, and he did not know how the survivors were rescued.

Details 'unclear'

"Whether it's in lifeboats, whether they've been picked up by other vessels is unclear," he said.

"Details are very scant at this stage."

A coastguard spokesman in the southern South Korean port of Busan, where the ship is based, said that there were eight Koreans, eight Chinese, 11 Indonesians, 11 Vietnamese, three Filipinos and one Russian on board.

Another South Korean fishing boat was involved in the rescue after reporting the accident to its home port, the spokesman said, and it also asked for help from New Zealand.

Source: Agencies