A cunning radio hacker has hijacked a police radio frequency during a car chase in regional Victoria.

The hack happened after an alleged attempted armed robbery, while officers were giving chase. They were trying to catch a man armed with a firearm who had attempted to rob a shop in Sale about 7pm on Tuesday, before fleeing in a stolen car with a woman.

"Throughout the incident there were a number of disruptions during the radio transmissions which are being investigated," Victoria Police spokeswoman Lauren Kells said on Wednesday. It's not known exactly what instructions were being given over the illegal broadcasts.

The pair were pursued to the nearby town of Traralgon where the 22 year old woman from Drouin was arrested. A 21 year old man from Warragul man was later arrested on the roof of a nearby shed.

The pair are in custody and assisting police with their inquiries.