An explorer woke up to find a polar bear's jaws around his head.

Sebastian Plur Nilssen was attacked last week as he slept in a tent in Norway despite protecting it with a trip-wire hooked to a early warning flare.

The 23-year-old was dragged screaming from the tent with his head clamped in the animal's jaws.

The polar bear's teeth pierced Nilssen's lung as it fought for a better grip and narrowly missed a main artery in his neck.

"It was so strong I could not fight, I grabbed for my shotgun and tried to shoot it but [the polar bear] had snapped [the gun] in half," Nilssen said. "It must have been only a minute I was in his jaws but it felt like forever. It was a big bear, at one point it stood up on its back legs with me in its mouth, I was over eight feet off the ground and it seemed very high."

His 22-year-old expedition partner Ludvig Fjeld shot the bear four times to save Nilssen.

Nilssen was airlifted from the scene, bleeding heavily, and was rushed into an emergency three-hour operation.

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