McDonald’s may boast that all the beef in the burgers sold in its British stores comes from the UK and Ireland.

But anti-deforestation activists are calling on the fast food giant to demonstrate that the cattle are not being raised on a soy-based feed blamed for causing the widescale loss of trees in the Amazon and other parts of South America.

In a report in February, campaign group Mighty Earth revealed how land was being cleared to make way for soy plantations in the Brazilian Cerrado and Bolivian Amazon.

Now, in a follow-up report, they said “large industrial farms” were still selling to major global food companies that supply household names like McDonald’s, Burger King, Dunkin’ Donuts, Kellogg’s and Kraft Heinz.

Glenn Hurowitz, chief executive of Mighty Earth, told The Independent: “McDonald’s has to make sure its burgers aren’t destroying rainforests.

“Despite the positive past steps McDonald’s has taken, everything we know about their suppliers suggests they’re still chock full of deforestation.”

The report, called Still At It, said McDonald’s had expressed a “desire for collective joint action with its suppliers” about the problem.

The company had not provided information about its supply chain but “publicly available data shows that it is Cargill’s biggest customer in Europe”, the report added.

While Cargill is hardly well known, it is the largest private firm in the US in terms of revenue.

The Mighty Earth report in February used satellite images, drones and mapping information to find evidence of significant deforestation in areas of Brazil and Bolivia where Cargill and another major company, Bunge, buy from farmers.

“If McDonalds isn’t using responsibly produced British feed, it should at least make sure it’s not getting foreign feed from companies like Cargill. Issuing general statements isn’t enough,” Mr Hurowitz said.

He said it was outrageous that McDonald’s suppliers knew how to provide products to help make Big Macs and McNuggets without cutting down trees but were still “refusing to do it”.

Mr Hurowitz said there was more than enough degraded land available for use for such plantations so there was no need for further deforestation.

This is a view shared by the United Nations, many countries and major companies around the world.

The New York Declaration on Forests in September 2014 pledged to end deforestation by the private sector by 2020 and stop it entirely by 2030.

In February, The New York Times spoke to local farmers in Bolivia in the areas covered by the first Mighty report and was told by ones who had cleared forest areas that they had sold soy to Cargill.

Cargill and Bunge – the former is a signatory to the New York declaration, the latter is not – both said Mighty’s report seemed to inflate their role in deforestation in the area, the Times reported.

At the time, Cargill insisted “if a farmer has burned down its forest we’ll not source from that grower” and promised to investigate, saying it would “honour our obligations and our commitments”.

“We’ve committed to ending deforestation and to do our part in ending deforestation. Our word is our bond,” Cargill’s chief executive David MacLennan told the Times.

In an emailed statement, Cargill pointed to its own Report on Forests and said: "Cargill’s commitment is to end deforestation in our agricultural supply chains. Cargill was the only agricultural commodities company to endorse the New York Declaration on Forests in 2014 and we are committed to delivering against global and private-sector targets to protect forests.

"We work alongside a number of organisations who share our goal of ending deforestation.

"Some are critical, some are supportive; but in all cases, we benefit from these interactions as we work toward a common purpose.

"We have a proven track record protecting forests and are proud of our progress. Yet we know we have more work to do. Recent reports highlight some of the hurdles on this journey, particularly in Brazil and Bolivia."

It added it was "advancing sustainable solutions" in the Brazilian Cerrado and, in Bolivia, Cargill said it was "applying our experience from other regions and evaluating our sourcing to ensure we are aligned with our commitments".

"Our work on deforestation is also connected to our goals of increasing food security and improving farmer livelihoods, which is why we are being thoughtful about our approaches and timetables," the statement said.