They have taken over the woodland which inspired author AA Milne’s famous Hundred Acre Wood.
It is now home to thousands of poison-resistant rodents which locals fear are guzzling bird eggs and small mammals.
“I have treated normal rats in Ashdown Forest and managed to kill them all with conventional poisons. But the reports are obviously concerning ”Paul Craven, local pest controller
Fears have been raised they could even harm tourists visiting Ashdown Forest in East Sussex by spreading disease.
But experts have warned laying down super-strength bait could well wipe out other animals that prey on the rats.
Local pest controller Paul Craven said: “I have treated normal rats in Ashdown Forest and managed to kill them all with conventional poisons. But the reports are obviously concerning.
“There are already stronger poisons out there that would work, but they are not approved for use outdoors.
“There is a concern that if these stronger rodenticides are put out into the wild, then you would have rats running around with extremely poisonous substances inside them.
“And that would potentially wipe out owls and other animals that prey on them. We’re tied by what poisons we can use.
“So if this became a real problem, it’s up to the Government to decide whether to allow stronger poisons.”
Huddersfield University reseacher Dr Dougie Clarke, who revealed the problem, warned the rats could even threaten humans.
He explained: “I think people should be concerned about these resistant rats because of public health concerns.
“They carry disease and various other bacteria and viruses and they also damage buildings.”
Yesterday Ashdown Forest spokesman Steve Alton claimed that poison-resistant rats were “nothing out of the ordinary”.
He added: “Ashdown Forest is a big area and I would say 99% does not have rats on, and they are more likely to be found near the houses and other buildings.”