Seven people have been pronounced dead after a South Korean ship capsized off an island in southwestern Japan, the coast guard said on Wednesday afternoon, out of nine crew members found so far.

Authorities said that one member of the crew was alive, and described another's condition as unknown. Earlier, authorities said all nine were in “unknown condition”.

The coast guard is still searching for two more people who were on the chemical tanker, which flipped over after reporting trouble in a rough sea.

The coast guard said it received a distress call from the chemical tanker Keoyoung Sun, saying that it was tilting while seeking refuge from the weather near Japan's Mutsure Island.

The island is just off the southwestern end of Japan's main island of Honshu, about 1,000 kilometers (620 miles) from Tokyo.

The ship was completely capsized by the time rescuers arrived at the scene, the coast guard said. Footage on NHK television showed the ship completely upside down, a rough sea washing over its red underside.

The ship was carrying a South Korean captain, and its crew included another South Korean national, a Chinese national and eight Indonesians, according to the coast guard.

The tanker was carrying 980 tons of acrylic acid, officials said. No leak has been detected, and officials are studying what environmental protection measures may be needed in case there is a leak.

Acrylic acid is used in plastics, resin and coatings and can irritate the skin, eyes and mucous membranes, according to the US Environmental Protection Agency.

No other details, including how the ship capsized, were immediately known.