Japan and South Korea's coast guards were searching Wednesday for eight crew from a cargo ship that sank between the two countries, after 14 others were rescued.

"A total of 14 have been rescued," a spokesman for the Japanese coast guard told AFP.

"We don't know their condition and nationalities yet," he added, declining to be named.

He said six of the crew had been rescued by South Korea's coast guard, which was assisting the operation.

Eleven of those rescued so far were "unconscious", the Jeju Coast Guard told AFP, adding that the rescued crew members were being transported to Japan's southwestern Nagasaki.

The Jin Tian sent a distress signal late on Tuesday evening from a position around 110 kilometres (68 miles) west of the remote and uninhabited Danjo islands in far southwestern Japan.

Three private ships were in the area and helped pick up several of the stranded crew members, Japan's coast guard said.

A Japanese coast guard plane and two ships were at the scene, with additional Japanese and South Korean vessels en route, officials from both countries said.

The ship's captain used a satellite phone to tell South Korean coast guard officials that he and the crew would abandon the sinking ship in the early hours of Wednesday morning, the Jeju Coast Guard said.

Contact with the crew was then lost.

Japan's government spokesman Hirokazu Matsuno confirmed that the country's coast guard was cooperating with South Korean authorities in the rescue mission.

The accident came as a cold snap hits much of Asia, with daytime temperatures in some of the Japanese islands nearest the rescue site reaching just three degrees Celsius (37 degrees Fahrenheit).

The 6,651-ton Jin Tian is registered in Hong Kong, and the crew on board included 14 Chinese nationals and eight people from Myanmar, Japan's coast guard said.

In 2020, a cargo ship with 43 crew and 6,000 cattle on board sank off southwestern Japan after being caught up in a typhoon. Two crew survived.