Off-roading is damaging Knettishall Heath, which is a designated Site of Special Scientific Interest.
Police have received reports of people using four-wheel drive vehicles on the heath during recent weeks and are warning people who want to participate in the activity that it is not something they can do anywhere they like.
A police spokesman said: “Not only is off-roading prohibited on the heath – as it is anywhere without the landowner’s consent – it causes considerable damage to the flora and fauna, as well as being potentially dangerous to legitimate users of the site.”
Knettishall Heath is home to thousands of species that are only found in the Brecks and is designated as a Site of Special Scientific Interest.
The noise and disturbance to the land disrupts the breeding of rare ground-nesting birds such as snipes and woodcocks and off-roading close to the Little Ouse and the flood plains destroys the homes of otters and water voles.
There have also been reports of scramble bikes being used on footpaths, which damage the paths and present a danger to walkers.
PCSO Claire Teakle, from St Edmundsbury Rural North Safer Neighbourhood Team, said: “Over the past few weeks there have been four-wheel drive vehicles off-roading on the heath. Some of the culprits have been caught and dealt with and it would appear that they were ignorant of the fact they could not off-road anywhere they pleased.
“Off-roading is not permitted without the consent of the landowner and has the potential to cause a great amount of damage – especially in an area with so many rare species of plants and wildlife.
“There is also the risk of injury it could cause to members of the public walking or cycling, especially if they have children or dogs with them, and to bird watchers who are not always highly visible.
“This site has taken years to develop but can be destroyed in seconds and once it has been damaged, it becomes inviting for others to off-road.
“We would like to send a strong message out to anyone caught off-roading that it will not be tolerated and we encourage members of the public to call us immediately if they witness any such activity.
“If caught, the offenders will be dealt with under Section 59 of the Police Reform Act, which can result in their vehicle being seized, the costs incurred by that and potential implications with their insurance.”