MYSTERY still surrounds a South Wangaratta collision on Friday night with a motorbike rider still missing.

A Victoria Police spokesperson said the rider, who was thrown from their bike as a result of a collision with a car on the Hume Freeway near the southbound on ramp about 6:30pm, could not be found when police arrived on scene.

“A ground search uncovered a pair of gloves and a helmet in a paddock between the Hume Freeway and Glenrowan Road, however there were no other signs of the rider,” they said.

“The driver of the car remained on scene and has spoken with police however only a bike and debris of the other party remained.”

The bike had no registration plates affixed, and police have been unable to identify the rider.

Police appealed to the public for information on Sunday, with officers concerned for the welfare of the rider and believed they could be seriously injured.

"Patrols of the area and a line search by police with assistance of CFA personnel, a door knock, checks with local hospitals and a search of housing yards nearby also proved fruitless," the spokesperson said.

The Police Air Wing also attended and checked the surrounding area without success while local officers searched the area in daylight hours on Monday.

Police are appealing for the rider to come forward and to anyone with information to make contact with police.

Anyone who witnessed the crash or motorists in the area at the time with dashcam are urged to contact Crime Stoppers on 1800 333 000 or submit a confidential report