Police have released CCTV footage following an armed robbery at a fast food restaurant in Derrimut last month.

A man entered the fast food outlet on Elgar Road just before 8.30am on Friday 10 October.

He ordered a meal and when it came time to pay he produced a knife and demanded cash.

He then grabbed some cash out of the open register and fled the scene.

No one was injured during the incident.

The man is described as Caucasian in appearance, 183cm tall and solid build.

He was wearing a black coloured jacket, black tracksuit pants, a black cap and sunglasses.

Police have also released an image of a man that they believe may be able to assist with their investigation.

Brimbank Embona Taskforce detectives are investigating the armed robbery and appeal for any witnesses to come forward.