A polar bear has been killed after it attacked and injured a guard who was leading tourists off a cruise ship in the Arctic.

It was shot by another guard "in an act of self defence", the cruise company said, after the animal left the other man "injured on his head".

The man, whose identity has not been revealed, was flown by helicopter to a town to receive treatment, the German Hapag Lloyd Cruises company said.

Norwegian authorities said the attack occurred when passengers on the MS Bremen cruise ship landed on the most northern island of the Svalbard archipelago, a region between mainland Norway and the North Pole that is known for its remote terrain, glaciers, reindeer and polar bears.

"He was flown out, was responsive, and is currently undergoing medical treatment," said Negar Etminan, a spokesperson for the cruise company, adding that the victim was not in a life-threatening condition.

She said all cruise ships travelling in the northern region are obliged to have polar bear guards on board.

Climate change threatens Svalbard's 3,000 polar bears

Arctic tourism to the region has risen sharply in the last few years and is now in high season. A Longyearbyen port schedule showed that 18 cruise ships will be docking at the Arctic port in the next week.

The attack comes after scientists warned polar bears are at risk of starvation due to shrinking sea ice caused by climate change.

'Daddy, where will the polar bears live?' Show all 3 1 /3 'Daddy, where will the polar bears live?' 'Daddy, where will the polar bears live?' Chilling: the polar bear's habitat is threatened by global warming children learn PA 'Daddy, where will the polar bears live?' A pupil by her school's wind turbine, near Littlehampton West Sussex PA 'Daddy, where will the polar bears live?' 'Children soak up the information like sponges, before disseminating it in a manner that brooks no argument' REX FEATURES

Scientists monitoring their activity in the Arctic found they have far higher energy demands than previously thought. Underfed bears were losing one per cent of their body mass every day.

But as their hunting grounds melt away, their chances of catching the seals they need to sustain themselves diminish.