RIO DE JANEIRO - Armed militia groups control more than half the territory of Rio de Janeiro, installing a reign of terror in poor neighborhoods that are home to nearly 2.2 million people, according to a study published Monday.
The criminal groups run extortion rackets and often act as de facto authorities in neighborhoods that last year represented 57.5 percent of the surface area of Brazil's second city, said a consortium including two universities, online watchdog platforms and a government anti-crime hotline.
The groups have largely overpowered drug gangs as the main criminal organizations in the 41 neighborhoods, home to 33 percent of the city's population, said the study.
A map produced by the consortium of armed groups shows the city -- known for its picturesque beaches but also its violent crime -- covered in blue dots representing militias across the west side of Rio, where the groups originated.
They are also present, with less density, on the city's north side, where drug gangs have traditionally held sway.
"The expansion of militia forces in Rio de Janeiro is striking given that they only began to organize in their current form in the 2000s," the study said.
By contrast, the city's biggest drug gangs, from which the militias often seize power, formed between the 1970s and 1990s, it said.
Militia members are largely former police officers or other security force members.
They initially formed as neighborhood watch groups to protect residents from drug gangs.
But they soon evolved into organized crime groups themselves, controlling sectors including internet service, cable TV, transportation and most recently construction.
© Agence France-Presse