A convenience store worker was tied to a chair by two would-be robbers who fled after setting the shop on fire.

The men, wearing balaclavas, entered the shop at Glenelg, in Adelaide, around 3.30am (AEST) on Thursday, police say.

They threatened the attendant and tied him to a chair, before setting fire to the store and leaving.

The victim managed to break free and raise the alarm.

Fire crews took about an hour to extinguish the blaze and damage is estimated to cost more than $100,000.

Police say the victim wasn’t injured but was taken to hospital as a precautionary measure.

AAP