Police are investigating the armed robbery of a Slacks Creek service station in which an employee was threatened with a knife last night.

Around 7.15pm a man entered the Kingston Road store armed with a knife before approaching the male staff member and demanding money.

The attendant was opening the till when the offender reached over the counter and stole a sum of cash before fleeing the scene on foot.

No one was physically injured during the incident.

The man is described as being Aboriginal or Torres Strait Islander in appearance, in his early 30s, approximately 175cm tall with a proportionate build and black short hair.

He was wearing a black hooded jumper and dark long pants.