More than half of the fires are in the massive Amazon basin.

Brazil's President Jair Bolsonaro signed a decree Wednesday to ban burning throughout the country for two months, government sources cited in local media said, as the authorities scramble to defuse the Amazon fires which have triggered a global outcry.

The blazes that have engulfed parts of the world's largest rainforest -- which is crucial for maintaining a stable global climate -- have also sparked a diplomatic spat between Brazil and Europe that threatens to torpedo a major trade deal.

The decree, which will be officially published on Thursday, prohibits any burning for the next 60 days, barring some exceptions in cases of approved agricultural and forestry practices, media reports said.

It comes as Bolsonaro's renewed demand that French leader Emmanuel Macron withdraw "insults" against him cast doubt on whether Brazil would accept the G7's offer of $20 million to help combat the fires.

Bolsonaro initially rejected the G7's offer, saying on Tuesday that he would be willing to accept it only if Macron withdrew his "insults," before appearing to change his mind to say Brazil would accept foreign aid on the condition that it controlled the money.

Studies show the 2.2 million-square mile forest is nearing a tipping point.

But later on Wednesday, the South American leader fired a fresh salvo.

"Only after he withdraws what he said... we can talk again," Bolsonaro told reporters Wednesday, referring to Macron.

He also accused France and Germany of "buying" the Latin American country's sovereignty with Amazon fire aid.

"It seems that $20 million is our price. Brazil doesn't have a price of 20 million or 20 trillion -- it's the same thing for us," he said.

Macron has accused Bolsonaro of lying to him about his commitments on climate change and vowed to block the EU-Mercosur trade deal involving Brazil that took decades to negotiate.

An aide to President Donald Trump said Wednesday the US was ready to assist with the Amazon crisis, but only if it involved the Brazilian government.

"We didn't agree to a G7 initiative that failed to include consultations w/ @jairbolsonaro . The most constructive way to assist w/ Brazil's ongoing efforts is in coordination w/ the Brazilian Gov," National Security Council spokesman Garrett Marquis tweeted late Wednesday.

Bolsonaro's latest remarks make him and his government appear "increasingly unhinged," said Robert Muggah, from a Rio de Janeiro think tank, the Igarape Institute.

Aerial picture showing smoke from a two-kilometre-long stretch of fire billowing from the Amazon rainforest. (AFP)

"There don't appear to be any adults left in the room with the ability or inclination to restrain his worst impulses," Muggah said.

No liars

On Monday, Macron rebuked the "extraordinarily rude" Bolsonaro after the Brazilian leader personally expressed approval for a supporter's Facebook post implying that Brigitte Macron was not as attractive as his own wife, Michelle Bolsonaro.

The Brazilian leader has since removed the comment from social media to avoid misinterpretation, his spokesman Otavio Rego Barros told reporters Wednesday.

Vice President Hamilton Mourao -- widely considered to be a moderate voice in Bolsonaro's government -- also weighed in publicly for the first time.

In an opinion piece published in the conservative Estado de S. Paulo newspaper, Mourao criticized an "international campaign" against Brazil and said the country "does not lie and nor does its president, its government and its institutions."

Bolsonaro said Brazil would accept bilateral aid to fight the fires, saying yes to Chile's offer of four aircraft. "We all love the Amazon, but the nine Amazon countries... have sovereignty" over it, Chile's President Sebastian Pinera said.

The outcry over the fires has alarmed industries in Latin America's largest economy. They fear potential boycotts of their products.

Global brands have threatened to suspend leather purchases from Brazil over the country's environmental policies, according to a document sent by the Brazil Tanneries Industry Center to the government.

Fires are also ravaging neighboring Bolivia where President Evo Morales and his rival in upcoming elections have suspended campaigning to deal with the blazes.

Burnt areas of the Amazon rainforest, near Porto Velho in Brazil's Rondonia state.

Bolsonaro on Wednesday supported Peru and Colombia's proposal for an emergency Amazon summit in September so regional countries could coordinate a strategy to protect the vast rainforest.

The latest official figures show 1,044 new fires were started Monday and Tuesday, taking the total this year to 83,329 -- the highest since 2010 -- even as military aircraft and troops help battle the blazes.

More than half of the fires are in the massive Amazon basin.

In the hard-hit northwestern state of Rondonia, thick smoke has choked the capital Porto Velho as fires blacken swaths of the rainforest.

But the defense ministry insists the fires are under control. It has published satellite data it says show a reduction in the number of blazes in the nine states spanning the Amazon.