Updated June 17, 2017 15:33:54

Seven US sailors are missing and their stricken ship is taking on water after it hit a Philippine-flagged merchant ship off the coast of Japan, the Coast Guard has confirmed.

The US 7th Fleet said the USS Fitzgerald collided with the merchant ship 56 nautical miles southwest of the fleet's home base at Yokosuka, south of Tokyo.

Japan's Coast Guard said seven sailors were missing.

Three crew members, including the ship's captain, Commander Bryce Benson, were evacuated by helicopter to a US naval hospital in Yokosuka.

Commander Benson was in stable condition, while the other two injured had lacerations and bruises, with other injuries being assessed, the Navy said.

Footage from Japanese broadcaster NHK showed significant damage to the Fitzgerald's side, and a person on a stretcher being lifted into a helicopter.

Japan Coast Guard official Takeshi Aikawa said the US ship was partially flooded because of damage and was not capable of moving by itself.

The Navy said the destroyer was operating under its own power but propulsion was limited.

Mr Aikawa said the container ship had not reported any damage or injuries to its crew.

The Coast Guard dispatched five patrol ships and an aircraft carrying medics to the site for search and rescue operations.

The USS Dewey, medical assistance and two Navy tugs were also being dispatched as quickly as possible, the US Navy said. Naval aircraft were also being readied to help.

It was unclear how the collision happened, and the US Navy said the incident was under investigation.

"Once an investigation is complete, then any legal issues can be addressed," a 7th Fleet spokesman said.

The waterways approaching Tokyo Bay are busy with commercial vessels sailing to and from Japan's two biggest container ports in Tokyo and Yokohama.

ABC/wires

Topics: navy, defence-forces, defence-and-national-security, community-and-society, united-states, japan

First posted June 17, 2017 09:12:27