A NASA scientist has contradicted Brazilian President Jair Bolsonaro over his defiance concerning fires raging in the Amazon rainforest using satellite images to back up his position.

Bolsonaro has maintained his position as Brazil's national institute for space research (INPE) reported nearly 2,500 new fires in the past 48 hours, despite the UN and French President Emmanuel Macron calling for action.

Britain's prime minister Boris Johnson said he would use the G7 summit to call for a renewed focus on protecting nature, his office said on Friday.

“The prime minister is deeply concerned by the increase in fires in the Amazon rainforest and the impact of the tragic loss of these precious habitats,” said a spokeswoman.

Doug Morton said satellite images showed the deforestation process in the Amazon was a "two-part process" — first the trees are cut and allowed to dry, then the same piles of wood that were cleared several months ago are being set on fire.

"They're burning an enormous bonfire of amazon logs that have been piled drying in the sun for several months," Morton told The Associated Press.

"So this is really the second part of the story that began with our observations of an increase in deforestation, that deforestation only precedes to someone being able to use those areas for agriculture if these areas are burned. "

Satellite image of Amazon with plumes of smoke from fires burning. NASA

Picture showing smoke rising from a fire in Rondonia state, northern Brazil. NASA

Picture showing smoke rising from a fire in Rondonia state. NASA

Picture showing smoke rising from a fire in Rondonia state. NASA

On the far-reaching effects of blazes, Morton explained: "Fires are directly burning into the Amazon rainforest and that releases the carbon stored in those trees.

"The carbon then enters the atmosphere as carbon dioxide or methane, where it contributes to the greenhouse gases that are causing climate change, bringing us a warmer and a drier planet.

"We also know that those fires are sending small particles, particles are trapped inside of the lungs of people living nearby, and those small particles are trapped in the lungs of the people that are exposed to that smoke further away.

"Those same particles also either absorb or reflect the sunlight so they're changing not just air quality but are actually part of our changing climate."

Bolsonaro's chief of staff, Onyx Lorenzoni, on Thursday accused European countries of exaggerating environmental problems in Brazil in order to disrupt its commercial interests.

"There is deforestation in Brazil, yes, but not at the rate and level that they say," Brazilian news website globo.com cited him as saying.

Morton spoke out for the INPE, the federal agency monitoring deforestation and wildfires, whose director was forced to step down in early August after standing up to the president's accusations that deforestation data had been altered to damage the reputation of his administration.

"The US and Brazil have had a very close scientific partnership for the last twenty years when I've been working in the Amazon," he said. "I was actually part of the team that helped develop Brazil's deforestation monitoring program with a new satellite that we launched in the early 2000s."

"Scientific and technical expertise for analysing and interpreting satellite images in Brazil is so high that after the development of that system, it has been running operationally with INPE without a lot of NASA involvement," AP cited Morton as saying.

NGOs bite back

As his government faced growing international criticism, Bolsonaro on Thursday said there was a "very strong" indication that some non-governmental groups could be starting the fires in response to losing state funds under his administration.

He did not, however, provide any evidence to back up this claim.

NGO Amnesty International directly blamed the Brazilian government for the fires, saying the responsibility to stop the wildfires "lies squarely with President Bolsonaro and his government".

"They must change their disastrous policy of opening up the rainforest for destruction, which is what has paved the way for this current crisis," Kumi Naidoo, Amnesty's secretary general said.

"Instead of spreading outrageous lies denying the scale of deforestation, we urge Brazil's President Bolsonaro to take immediate action to halt the progress of the wildfires that have been raging in the Amazon rainforest for several weeks," he added.

The WWF conservation group also hit back over Bolsonaro's claims, saying they served to divert "the focus of attention from what really matters: the well-being of nature and the people of the Amazon."

Around 60% of the Amazon rainforest is located in Brazil — its degradation could have severe consequences for global climate and rainfall.

Some social media who have called for action concerning the blazes have labelled the Amazon "the lungs of the planet".

Read more: Amazon fires cause activists to protest outside London's Brazilian embassy