The Department of Conservation wants to speak to four people seen inside an off-limits and potentially dangerous heritage site in Buller.

Doc's Westport principal ranger biodiversity Sean Judd says the group - a woman and three men, one of whom is wearing a distinctive cowboy hat - was captured on CCTV footage at the Banbury Mine, near Denniston, about 4.30pm on Friday, April 3.

The historic site is fenced off to ensure the protection of the mining heritage structures and artifacts, and to ensure public safety, he said.

“They’ve gone well past a fence and into an area where they shouldn’t be."

The area is a category one historic place and popular tourist attraction for people naturing in the Buller district, showcasing the old mine site, including the well-known Denniston Incline, Doc said in a statement today.

Many weathered artifacts remain there and hint at the living and working conditions from the 1880s, when coal was first sent down the Denniston Incline, to 1967, when the mine closed.

The CCTV…