A pet dog chained inside a kennel has been swallowed by a large python at Lismore in northern New South Wales.

The owner of the chihuahua-maltese dog discovered the carpet python inside the kennel with a large bulge in its body.

The dog's chain was still hanging from the snake's mouth.

A volunteer from the Wildlife Information Rescue and Education Service took the two-and-a-half-metre snake to a vet to see if the python would regurgitate the chain.

The snake is still under observation and it may need surgery.