Police are investigating an armed robbery which occurred at a service station in Barwon Heads late last night.

Investigators have been told that a man entered the premises on the corner of Geelong Road and Golf Links Road just before 11pm, when he produced a black handled knife and demanded the money till tray from the attendant.

It is believed the offender took a substantial amount of cash before leaving the scene west on Geelong Road.

The man is described as Caucasian, aged in his 20s, about 176cm tall with a medium build.

He was last seen wearing a black hooded jumper, black shorts with a blue stripe and black runners.

Police have released the below images of a man they believe can assist with their enquiries.