A worker at an adult entertainment store has been held at knifepoint during a robbery in Melbourne south-east last night.

Around 7.20pm a man walked into the store on Glen Huntly Road and asked a staff member about synthetic cannabis.

The employee showed the man where it was stocked behind the counter before the man pulled out a knife and waved it in front of the staff member.

He then reached over the counter and took a quantity of synthetic cannabis before running from the store.

Police have released CCTV of a man they believe may be able to assist with their inquiries.