Brazilian President Jair Bolsonaro says he will consider accepting a $US20 million ($30 million) offer of help from G7 nations to fight Amazon fires, but only after the French President Emmanuel Macron withdraws an "insult".

Key points: The Amazon fires have created a major crisis for Mr Bolsonaro's Government

The Amazon fires have created a major crisis for Mr Bolsonaro's Government A high-profile feud took a deeply personal turn when Mr Bolsonaro mocked Mr Macron's wife

A high-profile feud took a deeply personal turn when Mr Bolsonaro mocked Mr Macron's wife Mr Trump has come out in support of Mr Bolsonaro

Mr Macron announced the funding offer on Monday after talks at the summit of seven of the world's biggest economies in the French seaside town of Biarritz, but the offer was rejected by Mr Bolsonaro.

The two leaders have become embroiled in a deeply personal and public war of words in recent days, with Mr Bolsonaro mocking Mr Macron's wife and accusing the French leader of disrespecting Brazil's sovereignty.

Mr Macron has called Mr Bolsonaro a liar, and said Brazilian women were probably ashamed of their President.

French President Emmanuel Macron, centre left, and US President Donald Trump, centre right, at the recently concluded G7 summit. ( AP: Andrew Harnik )

The fires in the Amazon have created a major crisis for Mr Bolsonaro's far-right Government.

The Brazilian leader is losing popularity at home and finding himself increasingly isolated on the global stage over his response to blazes that threaten what many view as a key bulwark against global climate change.

His response to the fires is being closely watched by world leaders increasingly concerned by climate change, and could threaten Brazil's trade deals and powerful agribusiness sector, which is a crucial driver of its recession-plagued economy.

However, the offer of aid from the wealthy G7 nations has stirred up emotions within Mr Bolsonaro's nationalist Government.

Some officials are grateful for the much-needed help, and others view it as a colonial token that undermines Brazil's control of its lands.

Mr Bolsonaro raised Mr Macron's ire on Sunday when the Brazilian leader responded to a Facebook post that compared the looks of his wife Michelle, 37, with Macron's 66-year-old wife Brigitte.

"Do not humiliate the man hahahah," Mr Bolsonaro wrote, in a comment widely criticised as sexist.

Mr Macron, who has accused Mr Bolsonaro of lying about climate change policy, called the remarks "extremely disrespectful" to his wife.

France's first lady Brigitte Macron was the target of a social media post that Brazil's President weighed in on. ( AP: Julien de Rosa, pool )

On Tuesday, Mr Bolsonaro said he would only countenance accepting G7 money if Mr Macron retracted his earlier comments.

"First of all, Macron has to withdraw his insults," Mr Bolsonaro told reporters in Brasilia.

"He called me a liar. Before we talk or accept anything from France … he must withdraw these words then we can talk.

"First he withdraws, then offers (aid), then I will answer."

The French President's office declined to comment on Mr Bolsonaro's remarks.

A NASA satellite captures fires burning in Brazil this month. ( NASA )

Later, in an at times fraught discussion with members of his cabinet and governors of Amazon states, Mr Bolsonaro said he did not have anything against the G7 countries, but rather against the president of one of them — a thinly veiled reference to Mr Macron.

He also said he appreciated the environmental work of the G7, but said any efforts to harm Brazil's agribusiness sector would hurt Latin America's largest economy.

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But Mr Macron shrugged off the snub from the Brazilian President.

In a speech on Tuesday, the French leader said Mr Bolsonaro's interpretation was a "mistake".

He said the aid money wasn't just aimed at Brazil, but at nine countries in the vast Amazon region that also spanned Bolivia, Colombia, Venezuela, Ecuador, Peru, Guyana, Suriname and French Guiana, an overseas region of France.

Meanwhile, in a boost for the Brazilian leader, US President Donald Trump on Tuesday tweeted his support for Mr Bolsonaro, an ideological ally on the environment, China and trade.

The Brazilian President responded on Twitter saying they were successful in fighting the fires.

The number of blazes recorded across the Brazilian Amazon has risen 79 per cent this year, according to Brazil's space research agency.

As the personal feud plays out, the Amazon continues to burn. ( AP: Leo Correa )

Reuters/AP