Demonstrators in Rio de Janeiro, Sao Paulo and Brasilia, among other cities, on Friday demanded a decisive action to protect the Amazon and denounced the far-right President, whose initial reaction to the fires was to blame them on environmentalists, Efe news reported.
Facing intense criticism from Brazilian civil society, international organizations and European governments, Bolsonaro on Friday called an urgent ministerial meeting to map out a strategy to combat the fires.
The President, who took office in January, has moved to roll back environmental protections and to dismantle barriers to development in indigenous reserves.
Friday also saw mobilizations around the world to express concern about the Amazon fires.
Protesters gathered outside the Brazilian embassies in several Latin American countries, including Chile, Colombia, Mexico and Venezuela.
"The people heard the call of the Amazon. The Amazon cried out for its life and the world paid attention," environmental activist Thiago Avila told Efe at Friday's demonstration in Brasilia.
"Everybody came out, 166 protests in 140 cities in 30 countries said: the Amazon stays, Bolsonaro goes. It's been a long time since we've heard a cry like this in unison in so many places," he said.
The National Space Research Council (INPE), which monitors fires in Brazil using satellite imagery, said the number of blazes in the country was up 83 per cent compared with this time last year.
The INPE said in a report released on Tuesday that 52.5 per cent of the 71,497 fires registered between January 1 and August 18 were in the Amazon region.
Meawnhile, Porto Velho, capital of the northern Brazilian state of Rondonia, was enveloped early Friday in smoke generated by the wildfires.
Over the past week, the number of minors requiring treatment for respiratory ailments has tripled to 380 cases, according to the city authorities.
In the past week, according to the INPE, some 68 protected areas or indigenous reservations in the Amazon have been affected by fires.
( With inputs from IANS )