RIO DE JANEIRO, Aug. 26 (Xinhua) -- Brazil has sent warplanes to dump water on the burning Amazon rainforest, according to the country's Defense Ministry.

The ministry posted a video on Twitter on Sunday, showing one of the two C-130 Hercules aircraft that had departed from Porto Velho, the capital of Rondonia state, flying over the rainforest and dumping water out of its jets.

Brazilian President Jair Bolsonaro on Saturday told the press that the Amazon rainforest now "is not burning as people say," in a bid to assuage global concerns over the raging fires in the region.

On Friday, the president ordered the military to fight the massive fires, and over 40,000 troops have been sent to the region.

Research institutions and media reports said major causes of the record-breaking fires include the dry season and human activities.

Brazil owns about 60 percent of the Amazon rainforest, which covers an area of some 5,500,000 square km in South America. Scientists and environmental groups are worried that the fires will aggravate the climate change crisis and threaten biodiversity.