Brazil's Amazon rainforest has seen a record number of fires this year, according to new data from the country's space research agency.

The National Institute for Space Research (Inpe) said its satellite data showed an 84% increase on the same period in 2018.

It comes weeks after President Jair Bolsonaro sacked the head of the agency amid rows over its deforestation data.

Smoke from the fires caused a blackout in the city of São Paulo on Monday.

The largest rainforest in the world, the Amazon is a vital carbon store that slows down the pace of global warming.

It is also home to about three million species of plants and animals, and one million indigenous people.

Conservationists have blamed Mr Bolsonaro, saying he has encouraged loggers and farmers to clear the land, and scientists say the Amazon has suffered losses at an accelerated rate since he took office in January.

Meanwhile, US space agency Nasa said that overall fire activity in the Amazon basin was slightly below average this year.

The agency said that while activity had increased in Amazonas and Rondonia, it had decreased in the states of Mato Grosso and Pará.

Wildfires often occur in the dry season in Brazil but they are also deliberately started in efforts to illegally deforest land for cattle ranching.

Inpe said it had detected more than 72,000 fires between January and August - the highest number since records began in 2013. It said it had observed more than 9,500 forest fires since Thursday, mostly in the Amazon region.

In comparison, there slightly more than 40,000 in the same period of 2018, it said. However, the worst recent year was 2016, with more than 68,000 fires in that period.

The satellite images showed Brazil's most northern state, Roraima, covered in dark smoke, while neighbouring Amazonas declared an emergency over the fires.

Mr Bolsonaro brushed off the latest data, saying it was the "season of the queimada", when farmers use fire to clear land. "I used to be called Captain Chainsaw. Now I am Nero, setting the Amazon aflame," he was quoted by Reuters news agency as saying.