Swindon's rat population is on the increase because colonies are finding rich pickings among discarded fast food containers and bin bags in the town.

Pest control officers are warning people to take more care over disposing of their waste in a bid to control the vermin.

Rodent sightings have increased by 50 per cent on the previous year, with officers reporting about 60 new cases each month.

Senior environmental health officer Mike Poole, of Swindon Borough Council, said: "Dealing with rats is a bit like painting the Forth Bridge. You can clear an area of them completely, but if food is left out in the area again, they will soon return.

"Clearly rats are scavengers. That is their purpose in life, so obviously if they find somewhere with a regular source of food, they will stay in the area.

"My advice would be to ensure that bins are kept covered up and that you do not leave food lying about."

He added that a general pattern of milder winters, damp weather and increasing resistance to pesticides was also playing its part in boosting the rat population.

Rats are able to breed at an astonishing rate, with a mating pair producing a litter of about eight rats every six weeks. This rate is increased with warmer weather.

The council spends £62,000 a year on exterminating rats and recoups about £37,000 in charges.

And in March, Swindon Council approved an extra £10,000 to put towards clearing the town of its rodent problem.

The council charges £27 for its pest control service. A discount is available for those who pay in advance and there is no charge for Swindon Borough Council gold card holders, usually the elderly and financially disadvantaged.

The service was free until councillors agreed to introduce a nominal charge in October 1997.

Anyone with a rodent problem can call the council's environmental protection section on 07193 466071.