Detectives are hunting two men they believe are responsible for a series of robberies across Perth's northern suburbs.

Police say between November last year and February this year six liquor outlets in Craigie, Edgewater, Kallaroo, Hocking and Ocean Reef were robbed by a man armed with a knife.

On another occasion a liquor store in Edgewater was held up by two men armed with knives.

In each instance the men used beanies or shirts to hide their faces, demanded staff lie on the floor and then stole cash.

The repetitive nature of the robberies leads police to be believe the same men are responsible.

Detectives have asked anyone with information into the robberies to contact Crime Stoppers.