Captain missing and four crew severely burned, with 998-tonne Shoku Maru left gutted and leaning over in the water

The Japanese tanker Shoko Maru burning off Himeji port in Hyogo prefecture, western Japan.
The Japanese tanker Shoko Maru burning off Himeji port in Hyogo prefecture, western Japan. Photograph: Japanese coast guard/EPA

Staff and agencies in Tokyo

A Japanese oil tanker has exploded off the country's south-west coast near Himeji port, leaving one of the eight people aboard missing, the country's coast guard has said. Four others were severely injured in the accident on Thursday.

Fire gutted the middle of the Shoko Maru – the 998-tonne tanker, based in the western city of Hiroshima, was left leaning over in the water after the accident and was being doused by firefighting ships.

Seven people were rescued, four having suffered severe burns, the public broadcaster NHK reported. A search was under way for the missing man, the tanker's captain, it said.

Black smoke rises from Shoko Maru
 Black smoke rises from Shoko Maru. Photograph: AP

The cause of the explosion was unclear, said coast guard spokesman Koji Takarada. NHK said crew members had been working on the deck of the tanker at the time of the blast.

The tanker had unloaded its cargo of crude oil and was stationary close to the coast of Hyogo prefecture, about 280 miles (450km) west of Tokyo, when the explosion happened.

Akihiro Komura, an official from Syoho Shipping, a Hiroshima-based shipping firm that owns the vessel, told the AFP news agency that seven of the eight Japanese crew were accounted for but the fate of the captain was not yet known.

The 998-tonne oil tanker listing off the coast of Hyogo prefecture
 The 998-tonne oil tanker listing off the coast of Hyogo prefecture. Photograph: JAPAN COAST GUARD/AFP/Getty Images

"The ship unloaded crude oil at a port in Hyogo prefecture and the tanker was virtually empty when the accident occurred," he said.

"I heard that a crew member was using a grinder to remove paint and that seems to have triggered the blast, which we believe could have occurred when the remnants of the oil caught fire.

"It is a Japanese ship and belongs to our company. All the crew members are Japanese nationals. We have confirmed seven out of the eight are alive and one, believed to be the captain, is still missing."

News of the incident, which happened at around 9.30am, caused the prime minister, Shinzo Abe, to interrupt debate in parliament. "In waters off Hyogo [prefecture] a tanker has exploded and is currently in flames," he said in the chamber.

Himeji port is one of a number that sit along the Inland Seto Sea coast, where there are numerous pockets of heavy industry. The city itself is a popular tourist destination known for one of Japan's finest feudal castles.

The Associated Press and Agence France-Presse contributed to this report