A massive cane toad the size of a small dog has been captured in northern Australia.

The creature, nicknamed Toadzilla, is the largest cane toad ever found in Australia's Northern Territory.

It measures 20.5 centimeters (8 inches) in length and weighs about 840 grams (1.8 pounds).

Toadzilla was captured by FrogWatch environmentalists in a Darwin suburb on Monday night.

"It's a monster toad," said Paul Cowdy from FrogWatch. "We've never seen a cane toad this big. It's a male and normally females are bigger."

The second biggest cane toad to be captured in northern Australia was a female measuring nearly 15 centimeters.

Environmentalists say cane toads are highly poisonous and pose a real threat to native species.

The cane toad is a ground-dwelling predator and eats any prey it can fit into its mouth, including small lizards, snakes, frogs, mice, snails and aquatic insects.

The species was first introduced to Australia from South America in 1935 in a misguided attempt to control insect pests in sugar-cane fields.

Since then, the cane toad invasion has increased dramatically.

Environmentalists believe that there could be as many as 200 million cane toads living in Australia today.

Previous research has found that cane toads can travel almost 2km in a single night.