Commercial pickers are stripping ancient woodland of wild mushrooms for sale to restaurants and markets, the City of London Corporation has said.

The large-scale foragers are targeting Epping Forest, depriving insects and animals such as deer of a valuable food source and damaging the ancient trees which rely on types of fungus to protect their roots.

The corporation, which owns and manages the forest, is warning the fungus pickers that they could be fined or prosecuted for gathering mushrooms, which are protected under Epping Forest byelaws.

Fungi play a key role in Epping Forest's wildlife habitats and are a major reason it has protected status including as a Site of Special Scientific Interest and a Special Area of Conservation, the corporation said.

Epping Forest Guardian:

A haul of mushrooms seized from commercial pickers. Photo: City of London/PA

Since 2014, 18 people have been prosecuted for foraging, while forest keepers often issue verbal warnings.

In the most recent incident, legal action is being pursued over the seizure of a haul of mushrooms weighing 108lb (49kg).

Graeme Doshi-Smith, chairman of the City of London Corporation's Epping Forest and Commons Committee, said: "Fungi play an incredibly important role in the delicate balance of biodiversity which makes Epping Forest special.

"We welcome the millions of people who come to enjoy this protected site. But I urge our visitors to leave the fungi how they find them - untouched.

Epping Forest Guardian:

Pickers are damaging the environment and ecosystems. Photo: City of London/PA

"Our job is to protect this ancient woodland for everyone to enjoy. Hoovering up fungi on such a large scale is ecologically damaging and is simply unsustainable."

Epping Forest, London and Essex's largest green space, has more than a million trees, including ancient pollards of beech, hornbeam and oak, and is home to around 500 rare and endangered insect species.