Staff found a small snake in the passenger cabin on a Qantas Boeing 747 at Sydney International Airport

A small snake found on a Qantas Boeing 747 airliner led to 370 passengers being grounded in Sydney overnight, the airline said.

Staff found the eight-inch unidentified snake in the passenger cabin near the door before passengers were due to board at Sydney International Airport for a flight to Tokyo, Qantas said in a statement.

Australia's flagship airline said the passengers were accommodated in hotels overnight and left Sydney on a replacement plane on Monday morning.

The snake was taken by quarantine officials for analysis.

The Australian Agriculture Department said in a statement the snake was with entomologists and had not yet been identified.

Neither the department nor the airline offered any explanation of how the snake might have come aboard. No details of its likely fate have yet been made public.

The jet had been on an airport tarmac since it arrived in Sydney from Singapore on Saturday.

While snakes rarely pose aviation hazards, on January a 10ft python clung to the wing of a Qantas flight from the north-east coast city of Cairns to Papua New Guinea.

The python was dead but still attached to the wing when the two-hour flight ended in the national capital Port Moresby.