Brazil's President Jair Bolsonaro said on Tuesday it was a lie that the Amazon was being devastated by fire and accused his critics of having a “colonialist spirit”.
Maintaining the tradition of Brazil being first to speak at the UN General Assembly, the far-right politician heaped praise on US President Donald Trump for respecting his country's sovereignty.
Last week a Human Rights Watch report said Mr Bolsonaro had given a “green light” to illegal loggers and had failed to protect those defending the world's largest rainforest.
“The Amazon is not being devastated or consumed by fire. The media is lying,” he said, as his 32-minute speech went more than double its allotted time.
“It is a fallacy to say that the Amazon is the heritage of humankind, and a misconception confirmed by scientists to say that our Amazon forests are the lungs of the world."
His remarks were at odds with those of UN Secretary General Antonio Guterres, who opened the annual gathering.
Mr Guterres, at a UN summit on Monday, appealed to nations to reduce their carbon emissions and reliance on fossil fuels.
“As was emphasised at yesterday's Climate Action Summit, the climate emergency is a race we are losing, but it is a race we can win if we change our ways now," he said.
"Even our language has to adapt. What once was called 'climate change' is now truly a 'climate crisis', and what was once called 'global warming' has more accurately become 'global heating'.”
But Mr Bolsonaro, who was stabbed during the campaign that led to his election, hit out at his detractors.
He said that while every country had problems, sensationalist reporting in international media “aroused our patriotic sentiments”.
“Using and resorting to these fallacies, certain countries, instead of helping, behaved in a disrespectful manner and with a colonialist spirit,” he said.
“They even called into question that which we hold as a most sacred value, our sovereignty.”
The Amazon fires led French President Emmanuel Macron to accuse the Brazilian leader of having lied to him over the extent of the damage and the response made.
“One of these countries during the recent G7 meeting dared suggest applying sanctions to Brazil without consulting or even listening to Brazil,” Mr Bolsonaro said.
France and Ireland have said they might block a trade deal between the EU and some South American countries, including Brazil, because of Mr Bolsonaro's environmental policies.
But he said he was grateful to Mr Trump, a leader to whom he is often compared because of their shared policy views and outspoken nature.
“I thank President Donald Trump who summed up the spirit that should prevail among UN member countries: respect for the freedom and sovereignty of each of the member countries,” Mr Bolsonaro said.
Official figures do not support his claim that the fires are under control.
Amazon deforestation nearly doubled in the first eight months of this year, compared with the same period in 2018, to 6,404 square kilometres – more than twice the size of Luxembourg.