The fire in a sauna led to the evacuation of the conference hotel, which is regularly used by the NHS and medical associations.
Guests were taken to safety while the blaze was brought under control. No-one was injured and damage to the hotel was minimal. The spa is still closed.
The hotel recently hosted a British Medical Association event and the annual conference of the British Society of Cardiovascular Magnetic Resonance.
A statement issued by the hotel said: "Hotel staff immediately implemented the fire plan, evacuating guests as a precaution whilst the fire was brought under control.
"Whilst there has been some minor damage within the hotel, services in the adjoining Golden Jubilee National Hospital have not been affected."