Brazil’s President Jair Bolsonaro has said he might send the military to battle the massive blazes engulfing the Amazon amid an international outcry.
“That’s the plan,” said Mr Bolsonaro.
He did not say when the armed forces would get involved but suggested that action could be imminent.
Mr Bolsonaro has previously described rainforest protections as an obstacle to economic development, sparring with critics who note that the Amazon produces vast amounts of oxygen and is considered crucial in efforts to contain global warming.
Small numbers of demonstrators gathered outside Brazilian diplomatic missions in Paris, London and Geneva to urge Brazil to do more to fight the fires.
Neighbouring Bolivia and Paraguay have also struggled to contain fires that swept through woods and fields and, in many cases, got out of control in high winds after being set by residents clearing land for farming.
About 2,900 square miles of land has been affected in Bolivia, according to defence minister Javier Zavaleta.
On Friday, a B747-400 SuperTanker arrived in Bolivia to help with the fire-fighting effort.
The US-based aircraft can carry nearly 20,000 gallons of retardant, a substance used to stop fires.
Some 140 square miles have burned in northern Paraguay, near the borders with Brazil and Bolivia, said Joaquin Roa, a Paraguayan state emergency official.
He said the situation has stabilised.
In escalating tension over the fires, France accused Mr Bolsonaro of having lied to French leader Emmanuel Macron and threatened to block a European Union trade deal with several South American states, including Brazil.
The spectre of possible economic repercussions for Brazil and its South American neighbours show how the Amazon is becoming a battleground between Mr Bolsonaro and Western governments alarmed that vast swathes of the region are going up in smoke on his watch.
Ahead of a Group of Seven summit in France this weekend, Mr Macron’s office issued a statement questioning Mr Bolsonaro’s trustworthiness.
Brazilian statements and decisions indicate Mr Bolsonaro “has decided to not respect his commitments on the climate, nor to involve himself on the issue of biodiversity”, Mr Macron’s statement said.
It added that France now opposes an EU trade deal “in its current state” with the Mercosur bloc of South American nations that includes Brazil, Argentina, Paraguay and Uruguay.
Finnish prime minister Antti Rinne also expressed concern, saying he is “truly worried about the attitude Brazil seems to have adopted right now regarding” fires in the Amazon.
“Brazilian rainforests are vital for the world’s climate” and Brazil should do whatever it can to stop the blazes, said Mr Rinne, whose country holds the European Union’s rotating presidency.
Mr Bolsonaro has accused Mr Macron of politicising the issue, and his government said European countries are exaggerating Brazil’s environmental problems in order to disrupt its commercial interests.
Mr Bolsonaro has said he wants to convert land for cattle pastures and soybean farms.
Even so, Brazilian state experts have reported a record of nearly 77,000 wildfires across the country so far this year, up 85% over the same period in 2018.
Brazil contains about 60% of the Amazon rainforest, whose degradation could have severe consequences for global climate and rainfall.