BUENOS AIRES, Argentina – Three fans of the soccer club San Lorenzo de Almagro slipped past security guards after a closed-door practice in October and berated players on the field for their recent losses.

Jonathan Bottinelli, a star defender, told the men to leave. One of them lunged at Bottinelli and punched him in the face. Another hit him from behind. A few teammates rushed in to stop the fight, Bottinelli and other players said, but the beating continued, leaving Bottinelli, a club fan since childhood, with doubts about ever again pulling on the red-and-blue San Lorenzo jersey.

More than a decade after England finally tamed the roving bands of hooligans that long ravaged soccer stadiums in Britain, fan-related violence continues to stain the sport in Argentina.

The unrest in part reflects an increasingly violent Argentine society, where street crime has been on the rise. But much of the violence can be traced to hostilities between rival factions of barra bravas, the Argentine version of hooligan fan groups that use fists, firearms and knives, and operate like mini-mafias. They engage in legal and illegal businesses, including selling drugs, often with the cover and complicity of the police, politicians and club officials, according to prosecutors and others who have studied them.

Barra bravas are blamed for many of the 257 soccer-related deaths in Argentina since 1924, almost half of which have occurred in the past 20 years, according to Let’s Save Football, a nongovernmental organization in Buenos Aires that is working to eradicate violence in the sport.

“We don’t feel safe inside of our stadiums in Argentina,” said Monica Nizzardo, president of Let’s Save Football. “That is why families have stopped going.”

The head of the San Lorenzo barra brava, Cristian Evangelista, led the attack on Bottinelli, players testified in court, though they refused to name the other barras involved. Club officials did not respond to requests for comment. After the episode, the Argentine government canceled San Lorenzo’s next match while officials investigated.

Soccer violence became so rampant in the past decade that officials barred visiting fans from attending all but first-division matches for four years. The prohibition was lifted in August.

Visiting fans are not always the problem. After the storied club River Plate lost a match in June, relegating the team to the second division, its fans pulled apart their own stadium, throwing bleachers and metal poles onto the field as the police fired tear gas into the stands. Fans fought with one another and attacked reporters and the police, who used rubber bullets and water cannons to try to quell the chaos. An estimated 70 people were injured, including 35 police officers, and about 100 people were detained.

Asserting control over unruly fans is more complicated than in England, said experts who have studied soccer violence.

In England, many hooligans were working-class men looking for a weekend fight. In Argentina, the barra bravas have ties to politicians, the police and club management, and some of their leaders have gained the admiration of young fans. Politicians tap them as a “shock force” to muscle unions backing rival politicians. Prosecutors have accused barras of killing union workers.

“On Sundays they go to the stadium and wave the flag of the club to support the team,” said Gustavo Gerlero, a public prosecutor. “During the week they are giving support to politicians and union leaders as labourers and bodyguards by the very people that theoretically should be stopping them.”

A barra brava typically has a few hundred members. They chant songs and wave flags and organize the huge banners supporting their club. Away from the field they earn money from scalping tickets, parking cars, selling illicit drugs and, some prosecutors have said, taking a cut of the sale of players.

Gerlero suggested that a deadly attack in 2007 on a high-ranking barra brava member, Gonzalo Acro, was sparked by a dispute over a cut of the sale of striker Gonzalo Higuain to Real Madrid for 13 million euros (about $17 million). In September a court in Buenos Aires sentenced Alan and William Schlenker, leaders of one of the River Plate barras, and three of their associates, to life in prison for shooting Acro three times after he left his health club. Grondona, in the interview published last year, called the notion that the barra bravas were working with the clubs in the selling of players “absurd.”

The barra bravas of the top clubs, like Boca Juniors La 12, earn more than 300,000 pesos a month (about $70,000), with a group’s leader earning $15,000 or more per month, said Gustavo Grabia, a journalist and author of a best-selling book about the Boca barra brava.