A plague of super-sized rats are set to terrify residents in Britain with fears that many of the rodents have become immune to standard rat poisons.

The frightening warning comes from experts at the British Pest Control Association, who have suggested that over-the-counter rat poison pellets may have made the rodents stronger.

The size of rats has increased, with some of the pesky creatures now the size of a cat, experts say.

Scroll down for video