Two people are wanted by police over the fire near at Walters Bluff in Nelson earlier this month.
Nelson Police say they want to speak to a man and a woman who were in the area when the Iwa Road/Walters Bluff fire started on Friday 8 February.
They say the woman was the driver of a blue hatchback car in a vicinity of the Nelson School of Music on the corner of Collingwood Street between 4.15pm and 4.30pm.
The woman was seen to stop and pick up and item that was on the road directly adjacent to the roundabout.
The man was seen sitting beside a bicycle while eating on Iwa Road about the time of the fire around 2.30pm.
Anyone who may have information that would help identify these two people is asked to call 0800 08 02 19 or anonymously via Crimestoppers on 0800 555 111.