The Doncaster Road minor injuries unit recorded 18 incidents between January 2006 and April this year, according to figures obtained by the Conservative Party.

The majority of call-outs – 12 in total – were to deal with ants, but there were also two instances each of mice, wasps and biting insects, such as flies, infesting the premises.

Selby's Tory prospective parliamentary candidate Nigel Adams (pictured) said: "It seems to me the management at the town's hospital is handling the situation pretty well.

"Inevitably, there's going to be times when there's infestation, especially as the hospital is an old building. It strikes me they're doing a good job."

Selby War Memorial Hospital is one of 60 properties that comes under the control of York Hospitals NHS Foundation Trust.

A total of 690 call-outs were recorded to all health centres in that area during the two-year period.

Trust director of strategy and facilities Alison Hughes said: "We respond to any concerns raised by staff and the public, and have a pest control policy in place to handle any occurrences.

"We operate best practice in line with Department of Health guidance on the proactive management of pest control, including a regular programme of inspection visits as a preventative measure.

"The majority of call-outs have been to deal with ants and other insects."

A North Yorkshire and York Primary Care Trust spokesman said: "Some of our buildings are very old. Bootham Park in York, for example, is about 300 years old and is located near a railway line.

"In these circumstances, it's not surprising some incidents are detected. If an incident is detected, we have systems in place to quickly inform our pest control contractors and estates department to ensure the problem area is dealt with immediately." (s0535b739) Picture: Phil Sambrook