Canberra: A teenager has fought off an attack by a large saltwater crocodile in Australia's Northern Territory (NT).

Zefha Butcher was fishing with family on Groote Eylandt off the NT's northeast coast when he was attacked from behind by the 5.4 meter-long crocodile, local media reported on Friday.

The predator held the 19-year-old between its jaws in the water until Butcher was able to poke it in the eye and escape to safety.

"It was a really big one that attacked me from the back of the leg," he was quoted by News Corp Australia on Saturday.

"It was hard, like being hit by a car. Then it grabbed me at the top of my waist between my hip bone and thigh and tried to lift me out of the water then fling me into the water in a death roll.

"It took a couple of tries but I was able to get with my thumb first and it didn't let go then I got it an eye with my finger and it opened its mouth."

After escaping from the crocodile, Butcher was taken 200 km to the nearest hospital where he was treated for bites to his legs and hand.

Rangers captured and euthanized the crocodile, which was also responsible for several attacks on dogs in the area, days after the attack in mid-May.

Saltwater crocodiles can grow longer than six meters and are much more aggressive than their freshwater relatives.

They kill large prey by dragging them underwater and rapidly rolling in a maneuver known as the "death roll."

There are approximately 200,000 mature saltwater crocodiles in Australia, more than half of which are in the NT.

Butcher said he was lucky that he was too big for the crocodile to lift him.

"I was too big and he couldn't lift me. He had me in the salt water while he tried to do a roll but I was too big and he couldn't roll me," he said.

(With UNI inputs)