Amnesty International on Thursday warned of growing violence across Brazil, particularly killings by police as law enforcement and criminals battle over turf in Rio de Janeiro, the country's second-biggest city.

In a report to the United Nations, which periodically monitors violence in conflict zones and other troubled areas worldwide, the human rights group highlighted the recent spike in killings by Rio police — 182 in the first two months of the year, or 78 percent more than a year earlier.

"Brazil has not taken enough steps to tackle the shocking levels of human rights violations across the country, including soaring police homicide rates," Jurema Werneck, Amnesty's director in Brazil, said in a statement.