Wildfires raging in the Amazon rainforest have hit a record number this year, with 72,843 fires detected so far by Brazil's space research centre (INPE), as concerns grow over right-wing President Jair Bolsonaro's environmental policy.

The surge marks an 83 per cent increase over the same period of 2018, the agency said on Tuesday, and is the highest since records began in 2013.

Since Thursday, INPE said satellite images spotted 9,507 new forest fires in the country, mostly in the Amazon basin, home to the world's largest tropical forest seen as vital to countering global warming.

Brazilian President Jair Bolsonaro, addressing a crowd at an International Youth Day celebration on August 16, said in a Facebook Live session Wednesday that NGOs are likely to blame for the Amazon fires, without evidence to back up such a statement. (Evaristo SA/AFP/Getty Images)

Images show the northernmost state of Roraima covered in dark smoke. Amazonas declared an emergency in the south of the state and in its capital Manaus on Aug. 9. Acre, on the border with Peru, has been on environmental alert since Friday due to the fires.

Wildfires have increased in Mato Grosso and Para, two states where Brazil's agricultural frontier has pushed into the Amazon basin and spurred deforestation. Wildfires are common in the dry season, but are also deliberately set by farmers illegally deforesting land for cattle ranching.

President Bolsonaro blames NGOs

The unprecedented surge in wildfires has occurred since Bolsonaro took office in January vowing to develop the Amazon region for farming and mining, ignoring international concern over increased deforestation.

The right-wing Brazilian President said on a Facebook Live session Wednesday, without any supporting evidence, that non-governmental organizations could be burning down the Amazon rainforest to bring shame on his government after he cut their funding.

He said "everything indicates" that NGOs are going to the Amazon to "set fire" to the forest. When asked if he had evidence to back up his claims, he said he had "no written plan," adding "that's not how it's done."

There was worldwide outcry when the Notre Dame cathedral was on fire. Why is there not the same level of outrage for the fires destroying the <a href="https://twitter.com/hashtag/AmazonRainforest?src=hash&ref_src=twsrc%5Etfw">#AmazonRainforest</a>? <a href="https://t.co/VbSda5PYAK">pic.twitter.com/VbSda5PYAK</a> —@wwf_uk

Bolsonaro pointed out that his government had slashed NGO funding, which he claimed may be a motive for NGOs burning down the forest as they seek to bring infamy to his government.

"Crime exists," he said during the Facebook Live. "These people are missing the money."

"I used to be called Captain Chainsaw. Now I am Nero, setting the Amazon aflame. But it is the season of the queimada," he told reporters earlier, referring to the usage of fire by farmers to clear land.

Cannot be attributed to dry season

Space agency INPE, however, said the large number of wildfires could not be attributed to the dry season or natural phenomena alone.

"There is nothing abnormal about the climate this year or the rainfall in the Amazon region, which is just a little below average," said INPE researcher Alberto Setzer.

Thousands of fires have been detected in the Amazon rainforest in Brazil, South America's largest country. (CBC News)

People frequently blame the dry season for the wildfires in the Amazon, but that is not quite accurate, he said.

"The dry season creates the favourable conditions for the use and spread of fire, but starting a fire is the work of humans, either deliberately or by accident," Setzer said.

Bolsonaro recently fired the director of INPE after he criticized agency statistics showing an increase in deforestation in Brazil, saying they were inaccurate.

"I am waiting for the next set of numbers, that will not be made up numbers. If they are alarming, I will take notice of them in front of you," he told reporters.