Potty training is difficult enough for any toddler but one youngster has suffered a particularly dramatic experience after a carnivorous lizard emerged from the family toilet while he was using it.

The boy's mother discovered the 75-centimetre tegu lizard, a variety from South America, as she helped her three-year-old use the toilet, the Bergen aquarium in western Norway says.

The black, yellow-banded lizard weighed 1.5 kilograms.

"If it had had the possibility, I'm sure that it would have planted its teeth in anything that presented itself," Kees Ekeli, the head of the aquarium, which rounded up the reptile, told AFP.

"The little boy was learning to use the toilet rather than diapers and one might say that his training has suffered a serious setback," he said.

The lizard, which can hold its breath for up to half-an-hour, is thought to have escaped from a private importer despite the fact that bringing the species into Norway is against the law.

- AFP