Litter louts in Leeds are risking a "plague of super rats" descending on the city to feed on dropped burgers, chips and kebabs, it has been claimed.
Rats were feeding on discarded takeaways and other food
Leeds City Council said "super rodents" are evolving, which have more energy and live longer due to the food they are eating off the streets.
The problem was not just fast food being dropped but apple cores, banana skins and orange peels, they said.
A plastic box filled with 50 rats was to be put in the city centre on Monday.
The box, filled with food, was being used to illustrate how bad the problem could get, as part of a joint stunt by Leeds council and the Keep Britain Tidy campaign.
Councillor Steve Smith said: "Some people think it's okay to throw fruit peelings on the ground or feed crusts to the birds, because they biodegrade, but they are doing more harm than good.
"Such food takes time to biodegrade and only adds to the problems of attracting rats to our city."