A South West badger group has said it will do "whatever it takes" to save animals if a cull is introduced.
Protesters say there is no scientific proof that badgers spread TB
The Department for Rural Affairs (Defra) is considering a cull to tackle bovine TB and said they would be carried out by farmers.
Some farmers said they would not carry out culls for fear of recriminations.
The West Country Badger Action Group said it would trespass and break the law. But other badger groups are refusing to condone such actions.
Defra has admitted TB in cattle is the biggest animal disease problem it faces at the moment, and Devon is particularly badly affected.
Between January and November 2005, 1,144 farms - almost 20% of county cattle farms - were put under restrictions at some point because of positive TB tests. In Cornwall, it was 635.
Defra is now considering a mass cull of badgers to see if that will stop the spread of the disease.
A Defra spokesperson said: "Our assumption is that if a cull does go ahead it would be carried out by farmers, or their agents. Culling by the state is unlikely to be either efficient or cost-effective."
But some farmers said they were concerned this could leave them open to retaliation.
The West Country Badger Action Group said that its members would "do anything to stop the murder of badgers".
It said, if necessary, it would include trespassing and breaking the law, adding that it believed there had been "no official proof of a TB link between badgers and cattle".
The Badger Trust said it did not condone any such activity. It said its policy was never to take direct action, but only to present logical, scientific arguments.