RIO DE JANEIRO • Fires are burning in the Amazon rainforest at one of the fastest paces in years, Brazil's space research centre has said.

The National Institute for Space Research, which monitors fires using satellite images, reported on Wednesday that it had detected 75,336 fires this year in the world's largest rainforest, an increase of about 80 per cent from the same period last year.

The fires, most of them set by farmers clearing their land, are raging in uninhabited areas of rainforest and intruding on populated areas in the country's north, including Rondonia and Acre states.

The blazes are so large and widespread that smoke has wafted thousands of miles away to the Atlantic coast and Sao Paulo, the country's most populous city, according to the World Meteorological Organisation. Widely shared photos on social media showed darkened skies over Sao Paulo during the daytime, but researchers said they were working to understand whether that was connected to the fires.

On Wednesday, Brazil's far-right President, Mr Jair Bolsonaro, accused non-governmental organisations of setting the fires in the rainforest after the government pulled their funding, although he presented no evidence. "It could be, it could; I'm not saying it is, a criminal action by these NGO people to call attention against me, against the Brazilian government," he said. "This is the war we face."

He said the government was working to control the blazes.

Researchers, environmentalists and former government officials have been alarmed by the destruction of the Amazon rainforest, which is one of the world's most important natural resources and plays a vital role in absorbing carbon dioxide as global warming advances.

Deforestation of the Amazon has risen rapidly since Mr Bolsonaro, who was elected in October, took office and his government cut back on efforts to confront illegal activity in the rainforest. Critics say his policies have emboldened loggers, farmers and miners who want to clear out land illegally.

University of Sao Paulo's Professor Henrique Barbosa, who is part of the Physics Institute's Atmospheric Physics Laboratory, said the number of fires in the Amazon had risen during the past two presidential administrations but that they got worse this year.

He said the fires were a marker of the final stage of deforestation, in which trees are cut down for market and then loggers and farmers burn the rest.

"In reality, all the signs suggest it will get worse. There is nothing on the horizon that gives us the tiniest bit of hope something will be done to protect the environment in the next four years," he said.

NYTIMES