One crew member was killed and three were left missing after a steel-carrying cargo ship sank following an overnight collision with another ship off Japan, the coastguard and local media reported.

Japan-flagged cargo ships Senshomaru and Sumihomaru collided at around 2.10am on Sunday in Pacific waters off Chiba prefecture, according to local coastguard official Hiromitsu Kawaguchi.

"Senshomaru seems to have sunk at the scene of the collision. Coastguard patrol boat Matsushima rescued the captain of Senshomaru," Kawaguchi said.

The Senshomaru was later found on the seabed at a depth of 30 metres (98 feet) near the site of the collision, and the body of one of the missing crew members was found inside, Japan's Jiji Press and Kyodo News reported.

All four crew on the 499-tonne Sumihomaru were safe after the collusion. There were no details immediately available about the scale of the damage it had suffered, officials said.

Dense fog was covering the area at the time of the accident, Kawaguchi said, adding that oil had been seen in the water around the collision site.

The Senshomaru was carrying 1,600 tonnes of steel from Kashima in eastern Japan to Osaka, Japan's western commercial hub, he said.

The coastguard launched five patrol vessels, a helicopter, and a special search-and-rescue unit to find the missing men, while another special unit was working to contain the oil leak, Kawaguchi said.

The captain and the missing crew members are all Japanese men, he added.