Satellite images revealed that during the first two years of Lula's third term, the area of land cleared by mining halved compared to the government of his far-right predecessor Jair Bolsonaro.

Under Lula, illegal mining destroyed 4,219 hectares of Amazon rainforest -- equivalent to about 5,900 football fields -- in areas demarcated as protected Indigenous land by the state, where deforestation is a crime.

During Bolsonaro's four-year term from 2019 to 2022, the figure was 16,000 hectares, according to data from the MapBiomas monitoring network.

"So far, the (Lula) government has shown willingness to combat 'garimpo' (illegal mining) on Indigenous lands," Greenpeace spokesman Jorge Dantas told AFP.

"We came from a previous government sympathetic to the 'garimpeira' cause; willing to open indigenous lands for economic exploration," he added.

Under Lula, said Dantas, authorities have done more to evict mining camps and destroy the machines used for illegal extraction.

But despite improvements, Greenpeace warned in its "Toxic Gold" report that gold mining "continues to be one of the main vectors of deforestation, mercury contamination, loss of biodiversity, and social disintegration" in the Amazon.

And while the practice has been reduced in some Indigenous territories in the world's largest tropical forest, it has increased in others -- most notably in Sarare in the state of Mato Grosso, where land clearance for mining surged 93 percent from 2023 to 2024.

Factions linked to the Comando Vermelho, one of Brazil's largest criminal groups, are involved in "garimpo" in Sarare, "spreading violence and death threats," according to Greenpeace.

It added that gold taken illegally from the Amazon was exported around the world through various false verification mechanisms, with Switzerland the main destination.

Lula, 79, has said he wants to make Brazil a leader in the fight against global warming, in which carbon-absorbing forests play a key role.

The next round of UN climate talks are due to take place in the Amazonian city of Belem in November.

Some 8,000 Indigenous people from the Amazon rainforest and the Pacific converged on Brazil's capital Brasilia on Monday to demand a say equal to that of politicians at the conference.

Since Lula took office in January 2023, deforestation in the Amazon for all purposes has decreased, although forest fires driven by heat and drought have increased.

On a visit to the Amazon last week, Lula praised the "important role" played by Indigenous communities in the fight against climate change.

While pledging to end illegal Amazon deforestation, the leftist president has come under fire from climate activists for pushing a major offshore oil exploration project near the mouth of the Amazon River.