Loch Lomond National Park is warning the public of the dangers of blue-green algae after finding it in their water.

Rangers at the park have reported sightings of the organisms which are known to produce harmful toxins.

Posting on social media, visitors are warned to be careful as the blue-green algae can kill dogs and other animals.

For humans, it can cause rashes after skin contact and other illnesses if swallowed.

People are advised to keep themselves and their pets out of the water.

The algae blooms can make the water in the loch become green, blue-green or greenish brown as well as forming odours and foam on the shoreline.

The park says they aim to advise visitors when the warning is over but it can be difficult to predict as it could form and dissipate again within hours or days.

Anyone who spots the algae is encouraged to report it on an app called Bloomin' Algae which reports the presence of the substance.