Hospitals across Northern Ireland have been warned to prepare for up to a 20% surge in vermin infestations this winter.

Experts say the coldest snap for five years will cause problems for public services as rodents and pests seek shelter from plummeting temperatures outside.

Health trusts across the region have spent more than £125,000 fighting plagues of rats and mice in the past two years, according to internal documents released to the Belfast Telegraph.

Vermin were responsible for the majority of more than 4,000 call-outs of pest controllers by hospitals, surgeries and day-centres. As Christmas approaches, pest controllers have warned hospital staff to be on their guard against rat and mice infestations.

Simon McTier, pest controller at Cannon Hygiene, said: “Rodent problems absolutely increase in winter and you get anywhere up to 20% more in December than during the rest of the year. It’s the change in climate, the rain and the prospect of heat and food that tempts them into buildings.”

Premises operated by the South Eastern Trust, including Ulster Hospital and Downshire Hospital, were visited by rodent catchers 3,315 times for call-outs and routine checks between 2006 and 2008. In one incident in Lagan Valley Hospital, rats were found in a maternity ward. On several occasions in Downshire Hospital, mice and rats were found in the kitchens, and on one occasion rats were seen running around the Kids’ Club building.

Royal Hospitals in Belfast reported rodents in a maternity kitchen and cockroaches in a haematology lab.

Cockroaches were spotted outside a kitchen in Belfast City Hospital, while bedbugs were found in Erne, Tyrone and Fermanagh hospitals. At a day-centre in Coleraine, rats chewed their way through a fibre optic cable.

SDLP health spokesperson Carmel Hanna said local hospitals needed better guidance from pest controllers on how to prevent outbreaks.

Ms Hanna said: “Hospitals will obviously attract vermin for various reasons, whether it’s patients snacking and leaving crumbs around, or the fact that a lot of them are old buildings.

“However, I really do think this number of call-outs warrants some advice on how they can limit infestations.”

A spokesperson for the South Eastern and Belfast Trusts said hospitals had appropriate pest control measures in place.

“Pest control in health and social care trusts is arranged through a central contract and managed by trained officers in each of the trusts,” the spokesperson said. “Vigilance is also high across all trusts and staff are actively encouraged to report any suspected incidents so they can be investigated promptly and action taken if required.”