Smoke rising from cracks on the Denniston Plateau has Forest and Bird concerned that one or more underground coal fires have broken out.
But the mining company working on the plateau says the smoke is normal for coal mines.
Forest and Bird top of the south field officer Debs Martin said staff had visited the site and photographed smoke coming out of several cracks above a historic mine shaft.
Martin said the site was close to where Bathurst Resources had drilled core samples.
Bathurst's managing director Hamish Bohannan said the Denniston Plateau had smoldering in old workings "in a number of different areas".
Particularly on cold days "we'll get little vents of steam, maybe a bit of smoke".
He said the visible smoke was nothing out of the ordinary and was not related to the company's current activities in the area.
Bathurst was given permission by the Department of Conservation (DOC) to open-cast mine on the Plateau in June. The company started preparatory work on the West Coast site last month.
Martin said there was "too much of a coincidence". "There's little doubt this is linked to Bathurst's mining activities."
She said DOC should stop Bathurst's preparatory mining work until the fire or fires were extinguished.
"All efforts should now go into stopping the whole coal seam from catching alight. A major underground fire could seriously affect the unique trees and wildlife beyond the area that Bathurst has permission to mine," she said.
- The Press