"Due to the amount of destruction to the building by the fire we can't be 100 per cent, but there are two options, both of which are accidental," he said.
He would not say what the options were.
Insurance assessors were at the site yesterday and a notice from the Wanganui District Council posted nearby said the building had to be demolished and the site cleared by 4pm on October 30.
Patrick Norton, brother of owner Caroline, told the Chronicle last month it was likely the bar would be rebuilt on the same site.
Meanwhile, Mr Kirby said police inquiries into a suspicious fire in Bell St on September 29 were continuing, as was the investigation into another fire that gutted a historic homestead near Waitotara six days earlier.
He said police were interested in talking to anybody who picked up a male hitchhiker in Wanganui and dropped him off in the Kai Iwi-Maxwell-Nukumaru area on the evening of September 23.
Anybody who picked up a hitchhiker that day should contact Constable Jackson at the Whanganui Police Station on 06 3490638.