Greenpeace activists have attached themselves to the anchor chain of a massive cargo ship here in Sao Luis, at the mouth of the Amazon. As long as they stay on the anchor it's impossible for the ship to dock and load its cargo of pig iron which is destined for the USA. Pig iron is used in the production of steel for cars and is exported from Brazil ready for processing.

Over the past two years Greenpeace has collected evidence about a new rainforest scandal involving the production of pig iron. A report released today by Greenpeace shows how rainforest trees are being chopped down to make wood charcoal, which is then burnt in furnaces to make pig iron.

This is driving the destruction of the rainforest, but it’s not just the trees that are suffering. The wood is often taken from protected land which is the home of indigenous people like the Awa tribe who have relied on the forest for centuries.

And at the charcoal camps themselves people work under terrible conditions to feed the ovens with fresh wood. This is modern day slavery, where people are lured from their homes with the promise of money but landed with huge debts for accommodation and food which they cannot pay off. Often these people sleep with nothing more than a plastic sheet as shelter, breathing in charcoal particles and other pollutants as they shovel wood in and charcoal out.

Greenpeace activists have been holding up the cargo ship, the ‘Clipper Hope’, since Monday. They’re there because they want to end a cycle of destruction which starts in the Amazon rainforest and ends in car showrooms all over the world. They're also sending a message to Brazil's President Dilma, who is preparing to host the world's elite in Rio in a few weeks time. Dilma is currently considering whether to veto changes to the 'forest cod', a key law which has protected the Amazon for decades.