A swarm of super rats resistant to poison is about to invade a Wiltshire town, according to experts.
The warning comes after the discovery of a rodent at a food establishment in Swindon measuring 20 inches - the largest ever found in the town.
Justin Holloway of Prokill found the giant rat and has warned the mutant rodents are 'closing in' on Swindon.
According to the Mirror, Justin said: "One particular strain of rats were not so susceptible to rodenticides or the anti-coagulants served and, as a percentage of the total rat population, they become greater over time.
"As far as resistance is concerned, it is a growing issue and over a period of time I expect this to be a greater problem than it currently is, but establishing a time frame is harder.
"The implication is if you are a rat and you're not being taken on, you might enjoy a longer life and grow to a larger size, because you are not being taken down.
"If there's a good source of food and water it becomes a larger rat."
Speaking to the Daily Mail, he added: "Unless you can extinguish all of the genetic line the rise of super rats is on the horizon.'
In June, researcher Dr Dougie Clarke said: "I think people should be concerned about these resistant rats because of public health... they carry disease and various other bacteria and viruses.
"They also damage buildings...they cost billions of pounds of damage worldwide."
While the rats have been growing and changing, humans have been using the same anticoagulant rat poisons since the 1950s.
"With the use of rodenticides, normal rats are killed off, and then the resistant ones remain," says Dr Clarke.
"So it's a sort of time bomb of resistance building up over generations of rats."
He added: "We've tested 17 counties and every single one of them has got resistant rats - this was an amazing find to us. We didn't expect to have every single county to have resistant rats."
Giant super rats spreading across UK at rapid speeds
Video: Rat filmed eating bread roll at airport deli counter