Police have released CCTV and images following an armed robbery in Dandenong North last month.

Investigators have been told a man attended the Stud Road service station just after midnight on 29 November.

The man pressed the buzzer and was let in by staff, once inside he put a balaclava on, produced a large knife and demanded cash from the till.

The staff member complied and the man left the store.

The offender is described as Caucasian, 20-30-years-old and was wearing a black hooded top, grey track pants and black runners.

He was seen nearby getting into a dark coloured car, possibly a Hyundai Getz.

Anyone with any information is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential crime report at www.crimestoppersvic.com.au