Walkers are being urged to go to the toilet before climbing Snowdon after reports of human faeces being left along paths.
Snowdonia National Park Authority said it was a minority of visitors who are “not as well prepared” to blame.
It comes after a tour guide said she had to tell walkers to “mind the poo” on a hike at the start of the busy Easter weekend, which has seen tourists flocking to the national park in Wales.
Gemma Davies told the BBC she had seen “a lot of stool” in paper cups and under stones - and even saw someone relieving themselves on the railway on the way back down.
On Monday, an official at Snowdonia National Park Authority said it was “alarming and upsetting” to hear the reports of human faeces being littered across the beauty spot, which she called “a special and fragile environment”.
Helen Pye, the organisation’s engagement officer, told BBC Radio Wales Breakfast: “We really don’t want to see this impacting on people’s enjoyment on the area.
“Unfortunately it is a small minority who are perhaps not as well prepared, let’s say, and get caught short.”
But she said most visitors listen to the national park authority’s advice, which is to “go before you hike and use those facilities at the foot of the main paths”.
Ms Davies told BBC Radio Wales Breakfast earlier on Monday morning there was “terrible litter” on the route and at the summit when she led a sunrise hike on Good Friday.
Walkers have previously been told to not drop banana skins on mountain paths after several kilograms were found on Scotland’s Ben Nevis within days.
Ms Davies said the litter on Snowdon included “human stools, tissues, wet wipes” and it was “embarrassing” to have to tell tourists to “mind the poo”. The tour guide claimed the toilets were closed at the top and bottom of the mountain.
Ms Pye from Snowdonia National Park Authority said there were open toilets at the bottom of all of the main paths at Snowdon and she did not think there needed to be any more up the mountain.
“I think in terms of the fact it is an amazing, special, beautiful mountain environment, I think the most appropriate thing is to have toilets at the bottom of the paths and not be littering the mountain with things like that,” she said.”
“It is really just about people pre-preparing. The vast majority of visitors cope absolutely fine with being able to hike up the mountain and back down and just going before they hike.”
