A Norwegian Sea King rescue helicopter found the bodies at the accident site south of Bodo in northern Norway where their V-22B Osprey aircraft belonging to the US Marine Corps was reported missing on Friday evening.

The ministry said the bodies would be brought to Bodo prior to transportation to the United States.

It added the plane went down just south of Bode during a training mission as part of Cold Response military exercises involving 30,000 troops from NATO and partner countries.

An investigation has been opened into the crash amid first indications the aircraft hit a mountain.

Police lead investigator Kristian Vikran Karlsen said the search and rescue operation had been delicate owing to the bad weather -- "but they brought out the bodies, which was the main priority".

NRK television reported the plane's black box had been recovered.

About 200 planes and some 50 ships are taking part in the exercises, scheduled to continue until April 1.

The ministry said the deceased were marines assigned to 2nd Marine Aircraft Wing, II Marine Expeditionary Force and that, aside from the crew, nobody else was aboard.

Norwegian defence chief General Eirik Kristoffersen offered his condolences to the families of the victims while the ministry said the exercise would continue despite the poor weather.

Cold Response 2022 aims to test how Norway would manage allied reinforcements on its soil in the event that NATO's mutual defence clause were triggered.

Tensions between Russia and NATO have soared following Moscow's invasion of Ukraine, but the exercises were planned long before that offensive began on February 24.