Brazil on Sunday deployed two Hercules C-130 aircraft to douse fires devouring parts of the Amazon rainforest, as hundreds of new blazes were ignited ahead of nationwide protests over the destruction.
Heavy smoke covered the city of Porto Velho in the northwestern state of Rondonia where the defense ministry said the planes have started dumping thousands of litres of water, amid a global uproar over the worst fires in years.
Swathes of the remote region bordering Bolivia have been scorched by the blazes, sending thick smoke billowing into the sky and increasing air pollution across the world's largest rainforest.
Experts say increased land clearing during the months-long dry season to make way for crops or grazing has aggravated the problem this year.
"It gets worse every year -- this year, the smoke has been really serious," Deliana Amorim, 46, told AFP in Porto Velho where half a million people live.
At least seven states, including Rondonia, have requested the army's help in the Amazon, where more than 43,000 troops are based and available to combat fires, officials said.
The fires have triggered a global outcry and are a major topic of concern at the G7 meeting in Biarritz in southern France.
World leaders at the summit have agreed to help the countries affected by the fires "as fast as possible," French President Emmanuel Macron said Sunday.
His remarks come amid an escalating war of words with his Brazilian counterpart Jair Bolsonaro, who he has accused of lying over Brazil's stance on climate change.
Bolsonaro has denounced what he calls Macron's "colonialist mentality."
The fires threaten to torpedo a huge trade agreement between the European Union and South American countries, including Brazil, that took 20 years to negotiate.
Pope Francis on Sunday also voiced concern for the rainforest, which he described as a "vital" lung for the planet.
The latest official figures show 79,513 forest fires have been recorded in Brazil this year, the highest number of any year since 2013.
More than half of the fires are in the massive Amazon basin, where more than 20 million people live. Some 1,130 new fires were ignited between Friday and Saturday, according to Brazil's National Institute for Space Research (INPE).
The new data come as protesters plan to take to the streets across Brazil on Sunday, after thousands held demonstrations in the country and in Europe on Friday.