Brazilian President Jair Bolsonaro denied fires were ravaging the Amazon rainforest, despite data from his own government showing the number of blazes was increasing.
Mr Bolsonaro faced international condemnation for his handling of huge fires and rising deforestation in the Amazon.
He hit back at critics in a speech through a video conference addressing countries that share the world's biggest rainforest.
"A tropical rainforest doesn't catch fire," Mr Bolsonaro said. "So this story that the Amazon is burning is a lie and we have to fight it with real numbers."
Satellite data from Brazil's national space agency showed the number of forest fires in the country's Amazon area last month increased by 28 per cent from July 2019.
It showed there are now 6,803 blazes.
Experts say most fires are lit by people to clear land illegally for farms and ranches.
Last year, huge fires devastated the Amazon from May to October, sending a thick haze of black smoke thousands of kilometres away to Sao Paulo.
The fires in a forest considered crucial to curbing climate change caused worldwide alarm.
Experts said there could be even more fires during this year's dry season, which is only getting started.
The scrutiny is pressuring Mr Bolsonaro, who has called for protected Amazon lands to be opened for mining and agriculture.
He sent troops to the Amazon Basin, 60 per cent of which is in Brazil, to fight fires and deforestation, declared a ban on agricultural fires and appointed a task force to combat the problem.
Mr Bolsonaro said that was producing results, saying there was a more than 25 per cent reduction in deforestation year-on-year last month.
"We are making big, enormous efforts to fight fires and deforestation, but even so we are criticised," he told the meeting of the Leticia Pact, a group founded last year to protect the Amazon.
His government has been accused of selectively picking data by announcing the July drop in deforestation.
Despite the one-month decline, deforestation in the Brazilian Amazon set a record high in the first seven months of the year, the data from Brazil's space agency shows.
