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

Forty patients and eight staff at the Royal Devon and Exeter Hospital have been affected by the Norwalk-type bug.

The virus outbreak started at the end of last week, and three wards have been closed to new admissions to help control the spread of infection.

The hospital trust says it has not yet postponed any operations, but the situation is being regularly reviewed.

The virus can be brought into hospitals by visitors and the trust is advising friends and families to stay away unless visits are absolutely necessary.

"We knew that diarrhoea and vomiting viruses were in the community and we were disappointed, though not surprised, when we had the first cases in the hospital at the end of last week," said the hospital's co-director of infection control, Judy Potter.

"In response we have closed three wards to new admissions and will restrict transfers from them to other health or social care settings.

"We know that people can bring the virus into the hospital, so we ask the family and friends of patients to stay away unless their visit is strictly necessary."

She said people in need of emergency treatment or who had an appointment booked and had not been told directly to stay away should still attend the hospital.

But she asked that if people had been suffering with sickness or diarrhoea - or had been in contact with someone who had been - they should call the hospital and warn them before they arrived.

"Please think twice before coming to visit a relative or friend," said Ms Potter.