Police are hunting for an armed woman wearing tracky dacks who has stolen cash and cigarettes from service stations in Melbourne's inner north on three separate occasions.

The woman targeted the same service station, on Victoria Rd, Northcote, twice in six months, and another on High Street on January 27.

She stole money, a cash till and cigarettes in the separate robberies.

Investigators have released CCTV of the woman during one of the robberies. She is described as Caucasion in appearance, about 175cm tall with a medium build.