Thousands of indigenous demonstrators camped out in Brazil's capital to protest President Jair Bolsonaro's policies and an initiative that could take away their ancestral lands.

The protesters set up the "Fight for Life" camp outside the seat of power in Brasilia, near the trio of buildings housing the presidency, Congress, and the Supreme Court.

The protest camp will hold a week of demos and other activities against what the organizers, the Association of Indigenous Peoples of Brazil, 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 are participating. 

Tension has peaked with a Supreme Court case opening 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 forced off their ancestral lands, including under Brazil's 1964-1985 military dictatorship, which wanted to develop the Amazon rainforest.

Their attorneys argue having now returned, they should have the right to benefit from the protected status of official reservations.

Brazil is home to around 900,000 indigenous people. Their reservations cover some 13 percent of the country.
Environmentalists say protecting indigenous reservations is one of the best ways to stop the destruction of the Amazon, a critical resource in the race to challenge climate change.

According to official figures, deforestation in the Brazilian Amazon has surged since Bolsonaro took office in 2019. In the 12 months through July, a total of 8,712 square kilometers, an area nearly the size of Puerto Rico, of forest cover was destroyed.