Almost all the victims were male, 81.8 percent of them aged 12-29, and three-quarters of them were black, according to the NGO.
On average, more than 11 people a day were killed in police raids in Brazil in 2016, nearly a quarter of them in the state of Rio de Janeiro, which is facing a surge of violence since it hosted the Olympic Games last year.
The problem is acute in the favelas where around a quarter of the city's population of 6.5 million live, and where drug gangs control much of the territory.
Some 113 police officers have been killed so far in 2017, the Public Security Forum said.
"This year, the press has talked a lot about the death of policemen in Rio, but it is actually a national trend. The number of agents killed has increased by 17.5 percent over one year in all of Brazil," said Samira Bueno, the Forum's executive director.
The Forum pointed out that the increase comes amid a drop in the government's security budget.
"Our public security policy dates back to the 19th century, and has even worsened since then," said Elisandro Lincoln, a police representative with the Forum.
Bueno said the absence of an integrated national system for crime statistics meant that the 2016 figures could only be presented at the end of October, and that, according to preliminary data, 2017 was shaping up to be even worse.