A teenager armed with a loaded shotgun has been charged after allegedly trying to force his way onto a Jetstar flight in Victoria before being overpowered by passengers.

The 17-year-old from Ballarat allegedly climbed through a hole in the security fencing at busy Avalon Airport before making his way on foot to the plane.

The teen tried to climb the front stairs into the cabin, but he was overpowered by three passengers who noticed him carrying the shotgun.

Police were called to the major airport, near Geelong, on Thursday afternoon following reports a male with a firearm had attempted to board a Jetstar flight.

The flight which was carrying about 150 people was bound for Sydney.