Image caption The Mandarin rat snake is commonly found in Asia

Hundreds of passengers bound for Japan were stranded in Australia overnight after a snake was found on a Qantas plane at Sydney airport.

Staff found the 20cm-long (eight-inch) Mandarin rat snake in the cabin before passengers boarded the Boeing 747 on Sunday.

It is not clear how the snake, which poses no threat to humans, had got on the flight from Singapore.

A replacement flight left for Tokyo on Monday morning.

The 370 stranded passengers spent the night in hotels in Sydney.

The snake - about the width of a pencil - was found near the doorway of the cabin, a Qantas spokeswoman said.

It was taken away by Department of Agriculture officials and later killed to make sure it did not introduce non-native pests or diseases into the country. The plane would be fumigated before returning to service, officials added, in case it was not the only snake on board.

Australia's Agriculture Department said it "was looking into how the snake came to be on the plane, but isn't able to speculate at this time".

The Mandarin rat snake is commonly found in Asia. Adults can grow to more than 1.2m (four feet) long.

This is the second time this year a snake has turned up on a Qantas plane.

In January, a scrub python was discovered on the wing of one of the airline's planes as it flew between the Australian city of Cairns and Port Moresby in Papua New Guinea. The python died during the flight.