The earthquake-damaged Waiau Lodge Hotel, built in 1910, burned to the ground in the early hours of Saturday.
Investigators looked over the wreckage yesterday and said at this point it was being treated as suspicious.
Enquiries will include viewing CCTV footage and working with the local community to further investigate the circumstances surrounding the fire.
Hurunui District Mayor Marie Black said earlier this week that even though the hotel had been closed since it was damaged in the 2016 Kaikōura earthquake, it remained an important place.
"This building is of significance to a community where people come together and use it as a venue for socialising. All of those things... impact on community wellbeing," Black said.
"Shock and disbelief at this point is the reaction of the locals in Waiau as they come to terms with the loss of, one might call it an iconic building in the village."
