Brazilian President Jair Bolsonaro on Wednesday said, without presenting evidence, that non-governmental organisations could be burning down the Amazon rain forest to bring shame on his government after he cut their funding.
The fires have been burning in regions that threaten tribes and wildlife.
Bolsonaro, who wants to develop the Amazon, argued that NGOs set the fires to create problems for Brazil.
Activists condemned that claim.
CBS reported that Sao Paulo was dark on Monday as smoke from the fires in the states of Rondônia and Amazonas travelled over the city.
Brazil's space centre has detected 72 843 fires, according to Reuters.
This represents an increase of 83% over 2018 fires, and the highest number since 2013, when fire records began.
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