A total of 74 people have become ill after visiting a hotel in Newport.
An investigation is being carried out after 51 guests and 23 staff were affected by a viral infection, which is probably norovirus, at the Hilton Hotel in Langstone.
They started to become ill last Tuesday and suffered diarrhoea and vomiting.
Hilton Worldwide said the wellbeing of guests and staff was of “paramount importance” and it had brought in “stringent” health and safety measures.
Public health officials say the outbreak is not linked to a particular function or event, but the virus was passed by someone originally infected.