The survey, Slaughtering the Amazon, used satellite images, surveillance flights and undercover visits to assess deforestation on dozens of ranches in the Para and Mato Grosso states. It focused on three Brazilian companies that operate slaughterhouses, Bertin, JBS and Marfrig, and which control a third of beef exports between them.
Greenpeace claims that these companies source from farms that carry out illegal deforestation.
Several UK supermarket, including Tesco, Sainsbury, Asda, Morrisons and Marks and Spencer are claimed to use the meat in products like pies and ready meals.
The supermarkets have strongly denied the claims, pointing to their traceability mechanisms.