Rats could soon be roaming the streets and be as common as dogs, campaigners have warned.

The number of rats in the South-East has already risen by 21 per cent and could rocket if left unchecked, the group Encams said.

The anti-litter charity is to target the fast-food generation in a series of adverts being shown in the region's cinemas from today to try to stop the explosion in the rodent population.

Environmental health officers believe fast-food litter is one of the three main reasons for the growth in the number of rats.

Encams, which runs the Keep Britain Tidy campaign, found leftover food and litter from takeaways at 20 per cent of areas in town and city centres during a recent survey.

Regional director Angela Howard said: "Unless we curb our littering behaviour, it will be as common to see a rat roaming the street as it is a dog or a cat.

"Some of the main culprits are the fast-food generation and the lunchtime crowd who leave their burger wrappers, sandwich cartons, apple cores, leftover kebabs and chip papers for rodents to feast on."

Warm weather and cuts in council pest control budgets are also blamed.