Around 80 people on Coromandel Peninsula held a protest on Saturday against a bill which will speed up the consenting process for some large-scale projects.
The Fast-Track Approvals Bill will see projects put before a panel, with a minister having the final say.
Catherine Delahunty from Coromandel Watchdog of Hauraki group is worried it will make it easier to mine on conservation land.
The former Green MP said one mining company had already put up a gate in the Karangahake Gorge, preventing people from entering the area.
Conservation groups were worried the bill would override the Environment Court, councils, the Department of Conservation and iwi.
Infrastructure Minister Chris Bishop told Checkpoint earlier this month he could not guarantee a ban on new mining projects on DOC land or new coal mining elsewhere.
"Actually, one of the things that ministers will be looking at is the significance of a project regionally or nationally - and mining is included in the sectors we'll be looking at, alongside infrastructure, renewable energy, aquaculture projects, more housing growth and a whole range of other things."
Asked whether the new fast-track consenting process would give ministers too much power, he said it was "a deliberate decision" by the new government.
"The red tape and green tape in this country [have] held us back for too long. It costs too much to get resource consents for major projects, and we are cutting those costs and reducing the time so we can get on with decarbonising the economy and also building the infrastructure we need for the future."