Warning signs have been put up at Stackpole Lake and Bosherston Lily Pond after Natural Resources Wales identified blue-green algae at the Pembrokeshire spot, which can be very harmful to animals.

Warning signs have now been installed by National Trust Cymru.

A spokesperson for Natural Resources Wales shared: “Please ensure you and your pets do not come into contact with the algae or the water, and make sure you maintain basic hand hygiene.

“Blue-green algae naturally occurs in inland waters, estuaries and the sea. Blooms can form when their numbers become excessive.

“Bloom and scum-forming blue-green algae can produce toxins. These toxins can be very dangerous to animals.

“In humans, they can cause rashes after skin contact and illnesses if swallowed.”