Man on the run after armed robbery of service station in Sydney's inner west

A man is on the run after robbing a service station in Sydney's inner-west with a knife.

Police were called to the station on Unwins Bridge Road at Sydenham after the knifeman threatened the attendant and fled with cash about 1.40am.

The attendant was not injured.

Police said the offender is of Caucasian appearance, in his early to mid-20s, with a thin build, and was wearing a grey short-sleeve shirt, black pants, and a grey and black coloured top.

Police are investigating whether the incident is linked to two armed robberies of service stations at Ashfield and Canterbury yesterday.

Anyone with relevant information is urged to contact Crime Stoppers on 1800 333 000.