A campaign group is opposing plans to build a £200m motor racing circuit on common land in the south Wales valleys.
The Open Spaces Society says the circuit at Ebbw Vale will damage the environment on the edge of the Brecon Beacons National Park.
The group is calling on Blaenau Gwent council to reject the plans.
But developers say minimising environmental impact is a key part of the application, and they pledge to improve access to common land.
Project backers say the scheme would create thousands of jobs on the 830-acre (335 hectares) site.
The plans include an international kart track and motocross tracks as well as a technology park for research, development and support services in the automotive and motor sports sectors.
But Open Spaces Society general secretary Kate Ashbrook said that the development is earmarked for registered common land which the public has the right to use.
"Even if they get planning permission they cannot just charge in and tear up common land," she said.
"They will need to find suitable land to offer in exchange ....it's hard to see how they can find an extensive area of comparable land to make into a common.
'We urge Blaenau Gwent council to give full consideration to the devastating effect this development would have on Wales's unique countryside and common land, and to refuse the application."
The Heads of the Valleys Development Company, which is behind the plans, said the proposed Circuit of Wales development has been subjected to a rigorous environmental assessment process as part of the planning application.
A spokesperson said: "Minimising the impact on the environment is one requirement of planning regulations, and environmental issues such as ecology, landscape and lighting are fully considered.
"Whilst Wales has a huge network of common land, the Heads of the Valleys Development Company has nevertheless taken a very proactive stance in developing a strategy to find suitable replacement open access land and to make accessing specific areas of common land at our location easier than it is currently.
"Dialogue with the appropriate parties on this matter is continuing in a positive manner."
The spokesperson said the planning application is currently the subject to statutory before the council considers its decision.