Six patients have been affected by an outbreak of the norovirus bug at NGH prompting the hospital to warn those who have had diarrhoea and sickness not to visit.
This afternoon a spokeswoman for the hospital confirmed a minor outbreak, which is contained to Becket Ward.
To keep patients safe and prevent further spread of the virus managers have implemented "stringent infection prevention and control procedures", which include isolating the ward.
Norovirus is one of the most common stomach bugs in the UK. It sometimes known as 'the winter vomiting bug' because it is more common in winter, but can be caught at any time of the year.
The spokeswoman said: "This is not a decision we have taken lightly but it is important that we do all we can to keep our patients safe."
Becket Ward will remain closed to all visitors over the Easter period as a precautionary measure to lessen the chance of spread to patients, staff, visitors and other areas of the hospital.
Restricted visiting will be allowed only in exceptional circumstances.
The spokeswoman said: "We are aware that there is norovirus in the wider community and for this reason would like to remind everyone that if you do need to attend the hospital you should pay attention to your hand hygiene – including using the alcohol gels provided at the entrances to wards and departments – to protect yourself and help us protect our patients.
"Unless there is a life-threatening emergency, no-one should come to the hospital if they have suffered any diarrhoea or vomiting in the preceding 48 hours.
"We would like take this opportunity to thank our patients, their relatives, carers and visitors in advance for their understanding during this time."
Staff at the hospital are meeting daily to monitor the situation and will make an announcement as soon as visiting restrictions are lifted.