File photo shows Brazilian President Jair Bolsonaro attending the 55th summit of the South American trade bloc Mercosur (Southern Common Market) in Bento Goncalves, Brazil, Dec. 5, 2019. (Xinhua/Rahel Patrasso)

With feather headdresses, grass skirts and body paint, thousands of indigenous demonstrators camped out in Brazil's capital Monday to protest far-right President Jair Bolsonaro's policies and an initiative that could take away their ancestral lands.

Pounding wooden tent poles into the ground, the protesters set up the "Fight for Life" camp outside the seat of power in Brasilia, near the trio of modernist buildings housing the presidency, Congress and the Supreme Court.

The protest camp, which opened Sunday, will hold a week of demos and other activities against what the organizers, the Association of Indigenous Peoples of Brazil (APIB), call Bolsonaro's "anti-indigenous agenda," seeking to exert pressure ahead of a crucial Supreme Court ruling on native lands.

Indigenous groups in Brazil accuse Bolsonaro of systematically attacking their rights and trying to open their lands to agribusiness and mining.

A similar protest in June erupted into clashes, with three indigenous demonstrators injured and three police wounded by arrows. 

The latest camp opened peacefully. Organizers said there were 4,000 indigenous protesters from 117 ethnic groups.

The tension has peaked with a Supreme Court case opening on Wednesday on the issue of how indigenous lands are protected.

The agribusiness lobby argues Brazil's constitutional protection of indigenous lands should only apply to those whose inhabitants were present in 1988, when the current constitution was adopted.

However, indigenous rights activists say native inhabitants were often forced off their ancestral lands.

AFP