Japanese government officials have confirmed that one of the country's submarines collided with a commercial vessel off the main southern island of Shikoku at around 10:58 local time on Monday, February 8.
The incident involving the diesel-electric submarine JS Soryu and the Hong Kong-flagged bulk carrier Ocean Artemis occurred while the former was participating in a Japan Maritime Self-Defence Force (JMSDF) training exercise some 40 kilometres southeast of Cape Ashizuri.
Japanese defence minister Nobuo Kishi said that, as Soryu was attempting to surface, it accidentally scraped the hull of the bulk carrier.
The collision resulted in damage to the submarine's conning tower, dive planes, and communications equipment. However, the minister assured the media that the vessel was still capable of sailing safely under its own power.
Three crewmen on Soryu suffered minor injuries though hospitalisation will not be necessary, the defence ministry said.
Mr Kishi commented that the incident was "extremely regrettable."
Japan Coast Guard officials meanwhile reported no damage or crew injuries on Ocean Artemis, which had earlier left Qingdao, China, and was en route to the Port of Mizushima with 90,000 tonnes of iron ore at the time of the collision.
The Japan Transport Safety Board has stated that it will conduct an investigation into the incident.