Northland police are investigating a spate of suspicious fires in the past seven months

On the morning of May 20, 15 traffic cones were taken from works on Pataua North Road near Whangarei, covered in diesel, then set alight.

Another stack was found smouldering up the road.

Police are also investigating a series of bush fires in Matapouri, Tutukaka, Ngunguru and Pataua.