A share of the cattle supplied to Brazil's markets are fattened on illegally deforested Amazon land. To conceal that fact from buyers, the animals often are passed through many hands and holdings before being sold, Brazilian researchers said.

That process of "regularizing" beef makes it hard for buyers to ensure their supply chains are deforestation-free — one reason widespread forest loss continues, researchers said in a study looking at how environmental crimes in the Amazon basin are often interrelated.

To disrupt the activities of such networks and prevent illegally sourced products flooding global markets, making the connections clear is vital, said Ilona Szabo, executive director of the Igarape Institute, a Brazilian think-think that published the study this week.