More than 30 environmental activists blocked the entrance to Bathurst's coal mine in Canterbury on Monday morning.
The Extinction Rebellion protesters are calling on Bathurst to shut down the open cast mine.
Activists aged 16 to 65 locked themselves inside and around two vehicles with chains, and some were hoisted high up on tripods.
At least six police officers arrived mid-morning, and used large wire cutters to open the gate.
They moved some protesters aside, managing to escort two workers through so they could reach the mine.
Bathurst has applied for an extension to its 38ha Canterbury Coal Mine but the protesters want it shut for good.
The mine produces low sulphur coal, with much of it used to support the local dairy industry.
Activist Julie Thompson said the group wanted Bathurst to withdraw their request to expand the mine and would blockade the entrance until this happened.
She said the group had plenty of food to last them at least a week.
"We are in an ecological crisis and we cannot continue to burn coal the way we have been," she said.
The youngest of the group, Ciara Foley, said the impacts of coal were "devastating" and she wanted to do her bit to protect the future of the next generation.
Another activist, Zoe Deans, wanted the Government to support Bathurst to transition into a clean industry and urged Fonterra to act quickly on their commitment to phasing out coal.
Bathurst Resources chief executive Richard Tacon said if the mine shut carbon dioxide emissions would go up as coal is transported longer distances to Canterbury customers.
He said the company supported a just transition to a net-zero carbon economy by 2050.
Police were speaking to the group.
RNZ
