A snake has been caught after it wriggled free from a carry-on bag aboard a US flight.

The white snake, believed to be between four and five foot long, was found curled up under a duffel bag by a passenger on a 90-minute Ravn Alaska flight between Aniak and Anchorage on Sunday.

It is believed the reptile was brought on board by a passenger on a previous flight who disembarked and left it behind.

The snake, which is not venomous, was spotted by a child who was climbing on his seat towards the back of the aircraft.

Anna McConnaughy, who was in the plane at the time, said there no panic when an announcement came over the intercom to say there was a snake on board.

Instead, most of the passengers were curious to see the reptile - including the pilot, who came back to help.

After a short discussion on how to capture it, the reptile was pictured being put into a bag and safely stowed in an overhead luggage compartment by a flight attendant.

In a statement, the airline confirmed that a passenger had violated policy in bringing the snake on to the plane.

They did not confirm what kind of snake was on board or whether the passenger would face any criminal charges related to the incident.

The plane landed at Anchorage airport as scheduled.