Politicians and health bosses in west Wales reported a "sudden surge in tourism" and have asked holidaymakers not to visit Pembrokeshire, Carmarthenshire or Ceredigion.
First Minister Mark Drakeford has urged people to avoid unnecessary travel, adding that "if people don’t follow this advice we will have no choice but to use powers to enforce it".
Hundreds of cars have been seen parked along the roads leading up to Snowdon in Snowdonia National Park, Gwynedd, with the car park also full.
Mountain rescuers warned they cannot guarantee help amid thecoronavirus crisis as it could put them in at risk.
Gwynedd Council has asked anyone who is on holiday in the county to return to their main home.
We urge anyone who is considering visiting Gwynedd and Snowdonia at present not to do so. This is to stop the spread of the virus and to limit the impact of visitors on health and care services which are already under extreme pressure locally.
Visit Wales also posted on social media asking tourists to "Visit Wales later" and to avoid all unnecessary travel.
Council leaders, health bosses, AMs and MPs in west Wales have reported an "influx of tourists".
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.
Rhondda Cynon Taf Council said it would close all play areas across the borough until further notice to minimise social interaction.
"If necessary, we will close all public parks unless social distancing is taken seriously," council leader Cllr Andrew Morgan warned.
Neath Port Talbot Council has also said it will close its parks for four weeks.
The parks affected include Margam Country Park, Gnoll Country Park, as well as other parks and playgrounds across the county borough.
Leader of Plaid Cymru Adam Price has called on the Welsh Government to close caravan parks, second homes and tourist accommodation during the coronavirus crisis.
Whilst I am aware that some holiday parks have decided to play their part in reducing the potential demand on already under resourced services in these communities by closing voluntarily, I understand that this is not consistent.
What is the advice?
Everyone in Wales has been told to follow social distancing guidelines as governments try to control the spread of the coronavirus pandemic.
But certain groups and those with underlying health conditions have been told to strictly adhere to those measures to ensure they are further protected.
And for those who experience symptoms of Covid-19, or live with those who do, they have been told to completely self-isolate.
The Health Minister Vaughan Gething said he and the First Minister "are actively considering our legal powers to directly intervene".
"We're asking people to be responsible. And I really hope we take that advice seriously because I certainly don't want our healthcare system in any part of Wales or indeed the UK to be overwhelmed by people moving around.
"We are of course taking it seriously and if we need to act, we are prepared to use the powers that we have."
First Minister Mark Drakeford said: "We all need to follow this advice now to protect each other and our families and to help ensure our NHS is not overwhelmed.
"Social distancing includes avoiding all but essential travel and if people don’t follow this advice we will have no choice but to use powers to enforce it."
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