Saline bags have been 'tampered with' at North Cumbria University Hospitals Trust. Scott Barbour/Getty

Police are investigating an NHS hospital in Carlisle where saline bags are alleged to have been "tampered with".

North Cumbria University Hospitals Trust said a small number of saline bags that appeared to have been tampered with at Cumberland Infirmary were discovered by a member of staff on Wednesday 4 January. It is unclear how the bags were interfered with.

A spokesman said there were no indications that any patients had been adversely affected and that there had been considerable work to review security measures across the hospital since the discovery.

Dr Rod Harpin, medical director at North Cumbria University Hospitals Trust, said: "I can confirm that the trust contacted the police on Wednesday 4 January regarding a small number of saline bags at the Cumberland Infirmary in Carlisle which appear to have been tampered with.

"We immediately implemented our serious incident procedures and there is no indication that any patients have been adversely affected but we continue to monitor this closely.

"Patient safety is our absolute priority and we will continue to work closely with the police."

Saline is a solution of sodium chloride in water and is used for a variety of medical reasons including flushing wounds and intravenous infusions.

If patients have any questions or concerns, they can contact the trust on 01228 814247