In an appeal ahead of the weekend, the charity said its rangers were reporting considerable increases in illegal camping and littering at countryside and coastal locations over recent months. This had been affecting the trust’s conservation work as well as wildlife, grazing animals and farm tenants, it said. The warning came as thousands of people were expected to travel to some of the country’s favourite countryside sites, such as the Lake District and Eryri (Snowdonia) in the next few days.

Those planning to do so are asked to follow guidelines from the Countryside Code such as appropriately disposing of litter, using designated campsites, not lighting fires and leaving barbecues at home. The National Trust said the Lake District, Snowdonia, the Peak District and Dunstable Downs in the Chilterns Area of Outstanding Natural Beauty were among the areas cared for by the charity that had seen growing impacts from visitors, putting additional strain on countryside teams, taking conservationists away from vital work, and placing popular sites and nature at risk. Concerns were particularly growing over the rise in illegal fly camping, where people camp without the landowner’s permission and leave debris behind.

Ben McCarthy, the National Trust’s head of nature conservation and restoration ecology, said: “It’s infuriating when a small minority of thoughtless people leave their rubbish behind that impacts both our wildlife and other visitors who have come to enjoy the na.