Stonnington Crime Investigation Unit detectives are investigating the circumstances surrounding an armed robbery in Malvern in November last year.

Investigators have been told a man attended a service station on High Street on Friday 4 November 2016 about 3.10am.

The man, who covered his face with a bandana, made demands for cash from the store attendant.

As he made demands for cash, he showed the attendant the handle of a knife which was down the front of his pants.

The attendant handed over a quantity of cash and the offender fled the scene in an unknown direction.

The offender is perceived to be of Caucasian appearance, 165-175cm tall with a medium build, brown hair and a short brown beard.

The man, who is believed to be in his late 20s, was wearing a black long sleeve top and black cargo pants.

Detectives have released CCTV and images of a man they believe may be able to assist with their enquiries.