Landowners in the Forest of Dean, who claim wild boar are damaging their property, have been told they can shoot or trap the animals.
New colonies are being formed by dumped or escaped animals
The boar are believed to be from a domestic herd dumped in the Staunton area of Gloucestershire.
The local authorities said they have been unable to take action because the legal status of the boar was uncertain.
But officials say efforts to trace the owner have failed and the animals are now considered to be wild.
'Back of a truck'
Nigel Durnford, an animal welfare inspector for Gloucestershire Trading Standards said: "We would be prepared to re-home them, if anyone corralled them up.
"But it's up to the landowners to do what they like, they're not a protected species, it's up to them if they want to shoot or trap them."
Wild boar were hunted to extinction in Britain 300 years ago, but new colonies have been formed by escapees from domestic or commercial farms.
Forest Enterprise, which manages the local woodlands, is concerned about the animals returning to the area.
Deputy Surveyor Rob Guest said: "We view them as an unwelcome introduction and would be happy to see them gone.
"Re-introduction should be planned, not by virtue of animals being dumped out the back of a truck."