Police and mining opponents have turned out in nearly equal numbers to a blockade on State Highway 1 north of Whangarei.
Members of the Ngati Hau hapu are leading the blockade on the main road near Hukerenui in Northland between 10am and noon.
Northland police communications manager Sarah Kennett said police were taking a "low key approach" to the event, and were there to ensure minimal disruption to traffic.
A total of 25 police staff were spread out along the detour road, at both diversion points and where the protesters were located.
There were about 35 protesters at the site, she said.
Ngati Hau, along with members of the Puhipuhi Mining Action group, are protesting against gold and silver mining exploration in the Puhipuhi Hills.
They fear the drilling will lead to mercury poisoning of the waterways.
- Fairfax Media