This is the moment a massive 'Godzilla' monitor lizard was caught rampaging through a family's bathroom.

The crocodile-sized beast was discovered by resident Isarawat Sirijan, 62, when he was about to soak in the bath at home in Saraburi, Thailand on June 21.

Upon seeing the hulking creature resting on the tiles, he fled and called animal catchers for help. However, the local rescue team told him they were short-staffed and could only dispatch one person to his house.

Volunteer Chatpol Linnak arrived at Isarawat's residence and was surprised by the sheer size of the river leviathan. He enlisted Isarawat's help, and together, they squared off against the giant lizard.

Footage shows how the men pinned down the reptile against the wall as it swung its tail in resistance. The volunteers then covered its face to keep it from snapping at them, and later bound its jaws with some rope.

The family's pet dogs barked at the monitor lizard warily as it was dragged back to the river where it is believed to have emerged.

Chatpol said: 'I was curious because the homeowner called and told me a massive lizard was inside his bathroom. I have caught more than 100 monitor lizards, but this one is the largest I've ever seen. I thought it was a crocodile at first.'

Isarawat suffered a minor wound while wrangling the beast.

He said: 'I'm used to seeing monitor lizards because we live right next to the river. But I needed help this time because it was just so large.'

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.