The Angora restaurant in Whanganui city centre was badly damaged in a fire early Saturday morning.
Firefighters were called to the popular restaurant on the corner of Victoria Avenue and Ingestre Street about 1.20am on Saturday, and the fire took several hours to get under control.
The building was already badly-burnt when they arrived.
The Fire Service received multiple calls about the blaze, which appeared to be based at the rear of the premises, in the vicinity of the kitchen, acting area commander Gary Ward said.
Eight firefighters and two fire engines worked to control the fire from about 1.30am, and a crew remained there until 4am.
Police were called to the scene and by Saturday morning the restaurant, blackened and with blown-out windows now boarded up, was cordonned off.
Mr Ward said fire investigators were scrutinising the scene to determine whether or not the blaze was suspicious.