Police are investigating the armed robbery of a service station at Labrador in the early hours of this morning.

Around 2.40am a man entered the Frank Street business and selected some drinks to buy.

He then attended the counter and produced a knife, threatening the 25-year-old male store attendant while attempting to steal the cash drawer.

In an attempt to push the knife away, the store attendant sustained a minor cut to his hand before fleeing to a back room.

The man then stole a sum of cash from the register and ran from the scene.

He is described as being aged in his late 30s, wearing a New South Wales Blues Origin cap, khaki three-quarter length pants and a dark jumper.

Police investigations are continuing.