Campaigners said that coalition Government plans to cut red tape threaten mediaeval green spaces.
The Open Spaces Society expressed its concern that proposals by the Department for the Environment, Food and Rural Affairs to relax rules on common land mean more development could take place.
At present, Defra Secretary Caroline Spelman must give her consent for any structures such as fences, buildings, surfaced tracks and car parks on registered commons in England.
A few exemptions exist where there is a need, for instance, to stop vehicles driving on to common land or for nature conservation.
But plans by Defra to simplify the law could, the OSS said, make it easier for developers to put up ‘works’ on commons, on which the public has a right to walk.
Kate Ashbrook, the society’s general secretary, said: “At present it is necessary to obtain the Environment Secretary’s consent, in addition to any planning and other consents, for works on common land such as fences, buildings, surfaced tracks and car-parks, to name a few.
“The current exemptions apply in a few, limited cases relating to nature conservation or protecting the land from vehicles.
“The requirement for the Secretary of State’s consent is a vital safeguard for our unique, historic common; it makes it clear to all that commons are special and must be protected.
“They have survived largely unspoilt since mediaeval times and should not be mucked about with.
“The Open Spaces Society is consulted by law on all applications for works on common land, and we object to those which are against the public interest.
Common land carries right, to graze animals or collect wood for example. There are about 520,000ha (1.3m acres) of common land in England and Wales, covering a range of landscapes and habitats. The public has a right to walk on all commons and to ride on some.
The OSS welcomed Defra’s implementation of part of the Commons Act 2006 that enables the public to register common land that was left off the official lists in the 1960s.
Ms Ashbrook added: “Implementation of these provisions is long overdue. It is over five years since the act was passed.