Police are investigating an armed robbery at a Stawell milk-bar last night.

Investigators have been told that a man armed with a knife entered the Sloane Street store and demanded money from its attendant just before 7pm.

The woman repelled the offender, before he ran out of the premises without taking anything.

There were no injuries and no customers in the store at the time of the incident.

The man is described as about 176cm tall, with a slim build and pointy nose.

He was wearing gloves, a stocking mask and washed out or faded orange overalls with reflective bands around the legs.

Police are appealing to anyone with information about the armed robbery to contact Crime Stoppers on 1800 333 000 or visit www.crimestoppers.com.au.