Swansea Marriott hotel cancelled large bookings over the Bank Holiday weekend following a potential infectious disease outbreak.
Those booked to stay at the hotel had included Southampton Football Club ahead of its relegation clash with Swansea City.
On Tuesday Public Health Wales said it had been made aware of a "potential infectious disease incident" at the hotel.
The department said it was working with environmental health and Swansea Council to determine if further action is required.
Michael Downie, general manager of the 119-bedroom hotel in the city's Maritime Quarter, said: "We were made aware late last week of a small number of associates and guests becoming ill. As per our normal procedures, we notified large group bookings in order for them to find alternative accommodations, should they choose to do so.
"The Environmental Health Organisation were also notified at this time, however the cause of the illness remains unconfirmed. There have been no further reports of illness this week and the hotel therefore remains operational."
Downie said any claims the decision to cancel large bookings was related to the football clash were "completely untrue".