Image copyright AP Image caption The UH-60 helicopter appeared to have lost its rear rotor

A US military helicopter has crashed off the coast of the southern island of Okinawa, Japanese officials say.

The Kyodo state news agency said 17 crew members were rescued, and seven people were injured.

Japan's defence ministry said the crash happened near Camp Schwab, the US Army base on the east coast of the island.

Kyodo said police confirmed that the helicopter crashed as it tried to land on a ship at sea. The exact cause is not yet known.

Reports in Japan said the helicopter was a UH-60 Black Hawk, which has been deployed by the US military in Iraq and Afghanistan.

Images broadcast by the Japanese national broadcaster NHK showed the helicopter, with its rear rotor severed, on board what appears to be a cargo vessel.

It is not clear if the helicopter crashed into the sea or on board the ship.

Okinawa is home to several US bases and around 27,000 personnel. The deployment is part of the US-Japan post-war defence alliance.

A new US military base is planned for Okinawa, but it has been met with opposition by officials on the island.

Japan said last week that it would put a temporary pause on construction while talks with Okinawa officials continued.