A tiny snake "about the width of a pencil" is responsible for grounding a jet of 370 passengers.

While the eight-inch reptile didn't cause quite the same high octane scenes as his cold-blooded cousins in the Samuel L Jackson film Snakes On A Plane, it succeeded in raising the profile of the humble Mandarin Rat Snake.

The live specimen was found in the passenger cabin of a Qantas Boeing 747 in Sydney on Sunday night.


Snake on a plane! A Mandarin Rat Snake (pictured) grounded the Qantas flight at Sydney on Sunday

The Tokyo-bound flight was cancelled and the plane was fumigated as a precaution, News.com.au reports.

Passengers were accommodated in a nearby hotel and the snake was euthanised.

The snake is believed to have arrived aboard the jet on a flight from Singapore a day earlier, the Sydney Morning Herald reported.

"The Department of Agriculture is looking into how the snake came to be on the plane, but isn't able to speculate at this time," it said in a statement.

Though the snake, which is only "mildly" venomous, did not pose a threat to humans, it had the potential to wreck "ecological havoc" in the Australian environment if it had escaped the plane with a mate, Canberra Reptile Zoo herpetologist Peter Child told the Associated Press.

It's not the airline's first "snake on a plane" moment - back in January passengers were stunned to notice a nine-foot Amethystine python attached to the wing of a Qantas jet as it took off from Cairns.