Norwegian rescuers were searching on Thursday for a Russian helicopter which went down with eight people on board at sea off the coast of the Arctic archipelago of Svalbard.

“We have a rescue operation ongoing. There is bad visibility. No wind, but a lot of waves,” Tore Hongset, the leader of the rescue coordination operation, told Norwegian broadcaster TV2.

“We are physically looking for the helicopter.”

A spokesman for the join rescue coordination center for northern Norway told Reuters the fate of the helicopter and those on board was not immediately clear.

The helicopter was on its way from the Pyramiden settlement to the coal mining port of Barentsburg, but was later confirmed to have gone down in the ocean 2-3 kilometres from its destination.

Located around 700 kilometres north of the European mainland, Svalbard is governed under a 1920 treaty giving Norway sovereignty but allowing all nations that sign the treaty to do business there and to exploit its natural resources. There are now more than 40 countries that are party to the treaty.

Russian coal company Arktikugol runs the coal mine at Barentsburg, the main activity, which employs Russian and Ukrainian miners.