Three cell towers are believed to have been set on fire overnight - all in the south Auckland region.
Acting Detective Inspector Shaun Vickers of the Counties Manukau Police said police were investigating all three fires.
The first happened around 10.45pm in Papatoetoe's Ferndown Ave, Vickers said.
Similar incidents were then reported on Miller Rd in Mangere Bridge around 11pm and on Idlewild Ave in nearby Mangere around 12.30am.
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"The fires are being treated as suspicious and inquiries are under way into these incidents," Vickers said.
Anyone with information about the incidents or who saw suspicious activity at any of these locations is asked to contact Counties Manukau Police on 105 or Crimestoppers anonymously on 0800 555 111.
The fires are the latest of at least 18 suspicious cell tower fires, thought to be linked to conspiracy theories related to the rollout of 5G.
Last month a 37-year-old man appeared in the Manukau District Court over a Manurewa arson attack at a cell tower in the south Auckland suburb.