Fire has gutted a popular pizza bar in Adelaide’s east early this morning, more than 40 years after it first opened its doors.

Police and fire crews were called to the pizza shop on Lower North East Rd at about 4am by a witness who saw smoke coming from the building.

Firefighters took more than half an hour to extinguish the blaze.

Investigators now suspect embers in the pizza oven may have ignited a pile of wood.

No one was in the shop at the time and the damage bill has been put at $100,000.

The store's owners say they are insured and are hoping to be back in business by Christmas.

Meanwhile, a fire has caused $200,000 damage to a house at Port Germain, north of Adelaide near Port Pirie.