Scotland's largest health board has closed eight wards at a hospital at the centre of a norovirus outbreak after two more patients died.

It was confirmed last night they had died at the Royal Alexandra Hospital in Paisley, Renfrewshire, after contracting the winter vomiting bug. NHS Greater Glasgow and Clyde said in both cases it was due to underlying medical conditions, although the diarrhoea and vomiting associated with norovirus infection had been "a contributory factor" in one.

It comes less than a week after two other patients at the hospital died after contracting norovirus.

A further two wards have now been closed due to an increased number of patients with diarrhoea and vomiting, taking the total number of wards affected to eight. Some 34 patients are showing symptoms of the bug.

Dr Teresa Inkster, a microbiologist for the health board, urged visitors to wash their hands when entering and leaving the hospital.

She added: "Norovirus is a particularly prevalent virus common in the community and healthcare settings. Typically it has a sudden onset and can spread quickly and therefore we would urge relatives and any visitors who have experienced any symptoms of diarrhoea or vomiting within the last 48 hours not to visit the hospital. We would also ask that visitors are restricted to close family and friends."

Meanwhile, visitors are being asked to restrict their visiting to two Highland hospitals and, in some cases, not visit at all if they, or a family member, have been affected by diarrhoea and vomiting.

NHS Highland is aware of an increase in the number of cases of diarrhoea and vomiting in the community as well as cases in the hospitals. A small number of cases have already been confirmed as norovirus. Raigmore Hospital in Inverness currently has two wards closed to admissions, with restricted visiting to each. Caithness General in Wick has its Rosebank Ward closed to admissions and visitors are being asked not to come to the ward.

Dr Emma Watson, lead infection control doctor for NHS Highland, said: "We know this virus is in the community and it is likely that it has been brought into the hospital. This is why we are asking everyone to think twice before they come in as a visitor and, if you or a family member has had these symptoms, please do not come in. By doing this we will be able to limit to spread as much as possible."