Large-scale agribusiness operations clear large swathes of native forest to make way for soy plantations.

A Mongabay investigation, prompted by a report done earlier this year by the NGO Mighty Earth, suggests that customers buying chicken from some of Britain’s largest supermarkets and fast-food chains may be unwittingly fueling rampant deforestation in the Bolivian Amazon and Brazilian savanna.

Tesco, Morrisons and McDonald’s buy their chicken from Cargill, the biggest private company in the world, which feeds its poultry with imported soy. The U.S. food distributor purchases its soy from large-scale agribusiness operations that often burn and clear large swathes of native forest to make way for their plantations.

Ten years ago, soy traders agreed to stop buying soy from the Brazilian Amazon following severe pressure from activists, consumers and retailers such as Tesco and McDonald’s.

However, in the wake of this agreement known as the “soy moratorium,” global soy traders simply shifted their sights to nearby areas where deforestation is now rife in the Bolivian Amazon and Brazilian savanna — a region known as the Cerrado, part of which lies inside Legal Amazonia as designated by the Brazilian government.