Tourists have been urged to stay away from West Wales by health and council chiefs.
"As the coronavirus (Covid-19) pandemic progresses, it is crucial we all play our part in tackling this disease in what is an unprecedented challenge in modern times.
"In particular it is extremely important that everyone follows the advice from the government to slow and stop the spread of this virus and that we all do everything we can to support our essential public services, especially our NHS.
"The government has now urged the public to stay at home and limit all but essential travel and it cannot be stressed enough how vital this advice is.
‘One major concern that we are starting to witness is an influx of tourists into West Wales and the consequences this may have in the coming weeks and especially the serious risk that there will be an overwhelming, unnecessary pressure on our services and supply chains.
"As strong supporters of the tourism and hospitality industry here in West Wales, we fully understand the huge and grave challenges facing the sector and why some businesses may want to take this opportunity to bring in visitors at this time.
"However, our absolute top priority is the need to stop spread of this virus and also to protect our NHS from the increased pressures that tourism brings at a time when they will be stretched to the absolute limit.
"In line with the official government advice therefore and also in recognition of the interests of the resident population here in West Wales, it is with great regret that we are taking an unprecedented step and asking people not to come on holiday to Ceredigion, Pembrokeshire or Carmarthenshire at this time.
"We are collectively exploring every avenue to support all businesses affected by this crisis but the overriding concern has to be to keep people safe and well.
"Please do not underestimate the risk this disease presents and we would urge you to take all the appropriate steps to keep you and your family safe, and also help all those who live and work here in West Wales stay safe and well.
‘We promise you that Ceredigion, Pembrokeshire and Carmarthenshire will be just as amazing places once this is all over and we are looking forward to the day in the near future when we are once again welcoming everyone back."
The statement was issued on behalf of the following:
• Emlyn Dole, Carmarthenshire County Council leader
• Ellen ap Gwynn, Ceredigion County Council leader
• Maria Battle, Hywel Dda University Health Board chair