A service station attendant “shooed away” a knife-wielding man with a stick after the business was held up for the second time in one week.

Police said a hooded man entered ECCO Service Station on Bay Street, Port Melbourne, just before 7.20pm on Friday.

The man threatened a staff member with a knife and demanded cash. But the attendant refused to hand over any money, picking up an object from behind the counter, understood to be a stick, and forced the man out of the store.

“He shooed the man away, shooed him,” a police spokeswoman said.

The attempted armed robbery came exactly a week after the service station was held up at knifepoint.

A hooded man threatened staff with a box cutter about 8.20pm last Friday and is believed to have got away with more than $1000.

Police believe the incidents may be connected because the offender is of similar appearance.

Detectives described the offender from the first incident as caucasian, in his early 20s, about 170 centimetres tall, medium build with dark hair and trimmed sideburns.

In the latest incident police said the offender was wearing a blue zip up hoodie that has a fluro orange hood, and grey tracksuit pants.

Anyone with information can contact Crime Stoppers on 1800 333 000 or www.crimestoppers.com.au.