Investigations are ongoing after multiple fires near Selwyn River, south of Christchurch.
A police spokesman said officers at the scene were speaking to people in the area.
Police are calling for sightings of a 4WD vehicle that was seen in the riverbed close to the vicinity of the fires.
The suspicious fires occurred at around 4pm in the Selwyn Riverbed near State Highway One just north of Dunsandel.
Residents living nearby had been evacuated, but have now been allowed back into their homes.