PEST control experts have warned Trowbridge residents that rat numbers are on the up with more rodents venturing out in daylight hours.

Although West Wiltshire District Council statistics suggest the rodent population remains at a steady level, more people than ever are reporting seeing rats in the daytime.

Derek Strawson, who runs A4 Pest Control visiting homes throughout west Wiltshire, said rat numbers were rising and consequently business was booming. He said: "Rat numbers are definitely on the up and they just do not seem to be seasonal any more I get just as many calls in summer as in winter.

"Rats don't like open spaces and they need foliage or rubbish to hide behind, so there are usually fewer around in the winter, but not any more."

Rats are notorious for spreading disease including Weil's disease or leptospirosis, an infection found in rat urine, which can cause liver and kidney failure in the most extreme cases. Trowbridge town councillor John Knight said he believes there are more rats appearing in daylight hours.

He said: "My mother has suffered from problems with rat infestations in Adcroft Road and I think the unnerving thing for her was to see them around in the daytime.

District council pest control staff received 579 calls about rat infestations in 2002-2003.

Clive Harland, principle environmental health officer, said: "We do not seem to be suffering from the national trend of increases year on year. It does not take much to keep a rat alive and for a rat population to become established, so if people are going to feed birds in their gardens we would advise them to keep the food out of the way so that rats are not tempted by it."

More worrying are cases of rats resistant to present-day poisons.

Richard Strand, executive director of the British Pest Control Association said: "As long as the sewers are well sealed you do not have a problem."