By the time fire crews arrived the blaze was well under way. The fire took just over an hour and a half to put out.
An eyewitness said they saw five teenagers walking near the back of the pub, thinking they were going to tag property.
On Monday morning, O'Sheas Public House owner and former All Whites goalkeeper Alan Stroud said the fire started in a wood pile behind the pub.
"Kids set fire to the wood pile, all damage is out the back just waiting for power to go back on and we are good to go," Stroud said.
Crews from the Anzac, Christchurch City and Redwood stations were called to the scene.
Fenz shift manager Alex Norris confirmed crews arrived to find the wood pile on fire at the rear of the building. Norris said the fire spread toward the building.
"We responded with two fire trucks initially, one from Christchurch and one from Anzac.
"Police arrived on scene and advised that the building was well ablaze and so we responded with a further fire truck from Redwood."
It comes as police were called to at least three other small vegetation fires around the Shirley area on Sunday night.
Norris said the other fires were vegetation fires and one was started on a school grounds.
He confirmed crews responded at 8.45pm to a bush fire in a school grounds on Quinns Rd, Shirley.
A police spokesperson said: We’re making inquiries into at least two fires on Marshland Road last night.
"Scene guards were put in place for the night and officers will be undertaking further inquiries today."
Police say they are looking into the circumstances of at least two of the fires.
-With NZ Herald
