This is the terrifying moment a huge monitor lizard wandered into a family's home and ran across their sofa - inches from their sleeping grandmother .

The family were preparing for dinner when the large reptile emerged from a nearby canal and snuck into the property in Samut Prakan province, Thailand, on December 23 evening.

CCTV footage shows a woman bringing in food when she spotted the venomous monitor lizard inside the room.

The 5ft-long creature terrified the residents as it ran for the exit, sprinting across the sofa and grazing an elderly woman who was lying on the couch.

The house pets could be seen running in fear as the lizard scurried away to freedom.

Resident Laor Siri said: ‘My grandmother was really scared when the lizard ran behind her body. She is old so it was difficult for her to stand up in time. It could have bit her and hurt her.'

Asian water monitor lizards live in canals and ponds in large cities in Thailand where they feed on fish, snakes, frogs and scraps of food left by humans.

They are aggressive when threatened and have a mildly venomous bite which sometimes carries harmful bacteria.