With 10 months to go to the Confederations Cup and as the countdown starts to the 2014 World Cup, Brazilian officials said they would not tolerate fan violence.
The country, which last hosted the World Cup in 1950, is setting up a specialist police investigation centre to deal with hooliganism, Rio state secretary for security Jose Mariano Beltrame said, adding it would be based in the suburb of Leblon.
The news came after outbreaks of fan violence at club level, with 21 knuckleduster-wielding fans of Fluminense arrested on Sunday for attacking two fans of Vasco da Gama.
"We can no longer tolerate violence ... this is not an example of [the image] we wish to project at the World Cup. We must act with rigour," Marta Rocha of the civil police told O Dia daily.
The mother of one of those arrested told reporters: "I am ashamed of my son."
Police lieutenant-colonel Joao Fiorentini explained that the 21 had been thrown in the cells as "quite apart from the assault, there was theft and that is why they have been locked up. We are tightening the noose."
Leaders of the 'Young Flu' supporters club said those responsible faced being thrown out of the club. Last week, a Vasco fan was killed by thugs supporting Flamengo and last April a Flamengo fan was beaten to death by rivals from Vasco.