Police are investigating two armed robberies that occurred overnight south of Brisbane that are belived to be linked.

The first robbery occurred at a service station in Mackenzie at 8.40pm.

Two men entered the service station on Mount Gravatt-Capalaba Road and produced a knife and threatened the attendant.

The male attendant locked himself inside an office and the pair stole a quantity of cigarettes and tobacco before fleeing the scene on foot.

The second incident occurred at a service station on Logan Road at Underwood at 9.30pm when three men entered the business armed with knives.

They threatened the male attendant and stole a quantity of cash and cigarettes before fleeing the scene and getting into a vehicle.

No one was physically injured as a result of either robbery.

The three men are described as Pacific Islander in appearance and one was wearing dark clothing.

Anyone who has information that would assist investigators are being urged to contact police.

If you have information for police, contact Policelink by providing information using the online suspicious activity form 24hrs per day at www.police.qld.gov.au/reporting.

You can report information about crime anonymously to Crime Stoppers, a registered charity and community volunteer organisation, via crimestoppersqld.com.au 24hrs per day.