A pensioner used a spanner and spark plugs to fight off a crocodile after his friend drowned when their boat capsized in northern Australia.

The 72-year-old was catching mud crabs when one of the reptiles nudged their ten-foot boat causing it to tip over.

His friend, who was in his 50s, drowned after becoming trapped under the upturned hull.

The fisherman said he smashed one of the crocodiles on its head with a spanner as he dragged himself to safety during the three-hour ordeal.

Air Ambulance spokesman Ian Badham said: "In that time the crocodiles kept coming back at him.

"Eventually his cries for help were picked up by other professional crabbers in the area and they took the man back to the boat ramp, along with the body of his mate."

The survivor was treated for shock before being flown to hospital in Darwin.

Authorities have not yet released his identity or that of his friend.