A dragon-like monitor lizard whacked a pet cat with its sharp tail when they met inside a family's yard.

The 4ft-long reptile wandered into the property and was spotted by the residents and their moggy in Bangkok, Thailand, on January 15.

Footage shows the lizard standing its ground as the feline curiously approaches it before slapping it hard to make it leave.

The scared cat jumped to avoid the attack and fled unhurt while its owner remained beside the door, watching the scene unfold.

Asian water monitor lizards normally live in canals, swamps, sewers and ponds in cities in Thailand. They feed on fish, snakes, frogs and scraps of food left by humans.

The reptiles are aggressive when threatened and have a mildly venomous bite, which sometimes carries harmful bacteria. The Godzilla-like reptiles are also a protected species in the country so their population thrives.