(CNN) Brazil's president has called Swedish climate change activist Greta Thunberg a "brat" after she condemned violence against indigenous people who were killed in the Amazon.

"Greta has said that the Indians died because because they were defending the Amazon. It's amazing that the press gives space to this kind of pirralha," Jair Bolsonaro told reporters in Brasilia.

Pirralha is a derogatory Portuguese word meaning "brat."

Bolsonaro's comments come after Thunberg tweeted a video on Sunday and wrote: "Indigenous people are literally being murdered for trying to protect the forest from illegal deforestation. Over and over again. It is shameful that the world remains silent about this."

Her tweet referenced the deaths of two indigenous men of the Guajajara tribe who were shot dead on Saturday, according to Reuters

Indigenous people are literally being murdered for trying to protect the forrest from illegal deforestation. Over and over again. It is shameful that the world remains silent about this. https://t.co/u1eLE8t0K4 — Greta Thunberg (@GretaThunberg) December 8, 2019

The Guajarara tribe, who work to protect the rainforest , has been threatened by loggers who experts say have taken advantage of reduced controls and less oversight to seize control of forest lands.

The 16-year-old is currently in Madrid for the COP25 summit -- which could make or break the world's climate commitments . Around 25,000 people from 200 countries were expected to attend.

On Wednesday she told the conference that countries need to implement drastic emission cuts instead of finding loopholes to avoid taking real action.

"Finding holistic solutions is what the COP should be all about, but instead it seems to have turned into some kind of opportunity for countries to negotiate loopholes and avoid raising their ambition," Thunberg said. "Countries are finding clever ways around having to take real action."

She added that "almost nothing is being done apart from clever accounting and creative PR."

Thunberg gives a speech at the COP25 Climate Conference in Madrid on Wednesday.

Shortly after the right-wing president insulted her on Tuesday, Thunberg changed her Twitter bio to "pirralha."

It's not the first time that she has changed her Twitter bio in a tongue-in-cheek move, after she also updated it when US President Donald Trump mocked her.

"She seems like a very happy young girl looking forward to a bright and wonderful future. So nice to see!" Trump tweeted following Thunberg's speech at the United Nations climate action summit where she excoriated world leaders for not doing enough to tackle the climate crisis.

The next day she updated her bio to read: "A very happy young girl looking forward to a bright and wonderful future."