Police are investigating the armed robbery of a grocery store in Coffs Harbour last night.

About 7pm yesterday (Monday 20 July 2015), a man entered the store on Grafton Street as it was closing and threatened the shopkeeper with a knife.

He walked behind the counter, grabbed a plastic bag and emptied out the cash register.

The man also took some cash the shopkeeper was holding before fleeing the store towards Park Avenue Lane.

Police from Coffs/Clarence Local Area Command were notified and established a crime scene.

A search was unable locate the man and officers are now appealing for anyone with information about the robbery or the identity of the man to come forward.

He is described as being aged in his 20s, about 178cm tall with a medium build.

He was last seen wearing a dark grey hooded jumper, light blue jeans and dark shoes.

His face was covered by a blue and white cloth and he carried a 10cm knife with black handle.