Violent disputes over indigenous land have been growing across Brazil, sparking heightened militancy by native tribes angered by broken promises of compensation and slower government registrations.
A report by the Indigenous Missionary Council (CIMI), cited by the Folha de Sao Paulo newspaper on Sunday, said the number of territorial conflicts jumped from 82 in in 2006 to 99 last year.
The indigenous peoples are fighting to protect their resource-rich lands from invasions or encroachment by huge cattle ranchers, industrial-scale farmers, illegal gold miners and loggers.
In this huge country, one percent of the 191-million-strong population controls 46 percent of the cultivated land.
The indigenous population faces murders, death threats, lack of health care and education, and delays in registering land ownership, according to CIMI, created in 1972 by Brazil's National Confederation of Roman Catholic Bishops.
It reported an average of 55 murders of native people per year across the country between 2003 and 2011.
Tension is particularly high in the country's northern Amazon region, where the federal government is building the huge Belo Monte hydro-electrical dam across the Xingu River.
Angry indigenous activists frequently occupy the construction sites and occasionally take employees hostage to protest what they view as broken promises of compensation.
CIMI also highlighted a drop in indigenous land registrations by the government, from 145 under president Fernando Henrique Cardoso (1995-2002), down to 79 under president Luiz Inacio Lula da Silva (2003-2010), and only three last year under President Dilma Rousseff.