Police are investigating after a convenience store was robbed by a man armed with a knife in South Brisbane this evening.

Preliminary investigations indicate around 5:50pm a man with his face covered entered the Merivale Street business and approached the counter before demanding money from the employee.

The worker complied, handing over a sum of money and cigarettes which the man put in a blue backpack.

He then left the premises on foot.

The man is described as being aged in his early 20s, slim build, wearing a beige cap, black long-sleeved shirt, black pants and bum-bag around his waist.

No one was injured during the incident.

Investigations are continuing.