Patients' relatives are being asked to stay away from the hospital

It is the second time in a month that the hospital has been affected by the Norwalk-type bug.

Relatives have been asked to limit visiting while efforts are made by staff to control the latest outbreak.

Four wards are closed to new admissions and five more have also reported cases of diarrhoea and vomiting.

Elaine Hobson, the hospital's director of operations, said: "These viruses are more common in the community at this time of the year and were brought into the hospital again nearly four weeks ago.

"Our infection control measures are tried and tested but are being undermined because people who have had recent contact with the virus are continuing to visit patients.

"Our urgent plea to them is please stay away unless the visit is strictly necessary."