Police are appealing for public assistance following the armed robbery of a financial institution in Casino today.

About 10.20am, a man entered the institution on Walker Street with his face covered and armed with a knife.

It is alleged the man threatened a female employee, demanding money, before fleeing with a sum of cash.

Police were notified and officers attached to Richmond Local Area Command attended, established a crime scene and canvassed the area.

The man is described as being of Caucasian appearance, approximately 170cm tall, aged 18-25 years and of slim build.

At the time he was wearing a grey-coloured jumper, dark tracksuit pants with white stripes, and black and white sneakers.

Anyone with information is urged to contact Richmond Police via Crime Stoppers on 1800 333 000.