The Transport Safety Board has started an investigation into a near-collision involving a Maritime Self-Defense Force training ship last week in the Kammon Strait.
The agency dispatched two officials Tuesday to conduct an on-site investigation. The strait divides Honshu and Kyushu.
The MSDF's Shimayuki training ship nearly collided with a Panama-registered freighter carrying automobiles at 8:50 p.m. June 11, the Japan Coast Guard and MSDF said.
The 3,050-ton training ship was on an incorrect heading and came within 250 meters of the 20,000-ton freighter, the Coast Guard said.
That incident "was a serious near-miss that can't be overlooked," said an official in the 7th Regional Coast Guard Headquarters in Kitakyushu.
Defense Minister Itsunori Onodera said during a news conference Tuesday morning the incident was not "such a dangerous situation."
MSDF Chief of Staff Adm. Katsutoshi Kawano told a separate news conference later in the day that Miho Otani, commanding officer of the training ship, was questioned by the Coast Guard.
"I take the incident seriously," Kawano said.
An MSDF destroyer collided with a South Korean containership in the Kammon Strait in October 2009.