The Parliamentary Commissioner for the Environment has told MPs the Department of Conservation needs to charge mining companies more for using DoC land.
Jan Wright released a report in September on recommendations for mining on the conservation estate.
It includes opposition to the Minister of Energy and Resources having a say on whether mining happens on DoC land.
Dr Wright told MPs at a select committee on Thursday that she does not believe mining companies are being charged enough for access to land.
She says if the conservation estate is to be commercialised, DoC should be more commercial about it and get a proper access and rental fee.