PARIS — Interior Minister Bruno Le Roux called for calm Monday after riots over an alleged police rape engulfed suburbs around France, triggering fears of a violent contagion three months before the presidential election.

Police arrested 37 people late Sunday in the latest night of rioting over the arrest of Theo, a 22-year-old black man who was hospitalized with injuries from being sodomized with a police baton following his arrest on February 2.

The riots, which started in the Paris suburb of Aulnay-sous-Bois and quickly spread to Nantes, Lille, Marseille and other cities, carried echoes of riots that rocked France in 2005. Successive governments have spent billions of euros sprucing up immigrant-heavy housing projects, but many local youths feel the underlying causes of their anger — notably hiring discrimination and police abuse — remain unaddressed more than a decade later.

Politically, the thorny issues of the banlieues (suburbs), which have to do with deep-seated feelings of alienation among youths of immigrant origin, remain as divisive as ever. In the days following initial reports of Theo's violent arrest, presidential candidates quickly took sides, with far-right leader Marine Le Pen voicing her support for police and blaming the government for failing to crack down harder on rioters.

Meanwhile President François Hollande's Socialist government is trying to head off escalation by showing support for the victim.

"I am calling for calm," said Le Roux. "In a democracy, expressing anger, a demand or giving an opinion is totally legitimate. But smashing things, burning other people's property, destroying it, that is the behavior of rabble-rousers that have nothing to do with the acts they pretend to denounce."

Le Roux added that he would be "inflexible" in dealing both with rioters and any police action that happened outside "the framework of the law, the framework of professional ethics."

Echoes of 2005

Images of burning cars and hooded youths clashing with police over the past week prompted comparisons with the violence that swept France in 2005, when then President Jacques Chirac was forced to call a national state of emergency due to nightly pitched battles between rioters and police. Dozens of public buildings and hundreds of cars were torched in riots that set the stage for Nicolas Sarkozy's rise to power on a law-and-order platform.

The latest riots are on a much smaller scale, but just like in 2005 they stem from outrage over police brutality. This has frequently proved to be an explosive catalyst for rioting in immigrant-heavy suburbs where relations between police and young locals are tense at best.

Now, authorities fear escalation as outrage spreads around the country and details of an investigation challenge Theo's original testimony.

Shortly after surveillance video of Theo's arrest was released, all four officers involved were placed under formal investigation, one of them for rape and the three others for assault. Theo, who sustained a 10 centimeter anal tear from the incident, told BFMTV the officer had taken his baton and "kicked it into [his] buttocks."

"I was not myself," added Theo from his hospital bed. "I thought I was going to die." (Being placed under formal investigation is not the same as being formally charged with a crime, but is a big step in that direction.)

But on February 9, the IGPN internal police investigation unit declared that use of the baton had been "an accident," according to RTL radio, which obtained an initial version of the report. "At the end of [the police officer's] detention, the IGPN did indeed note ... the obviously non-intentional nature of the officer's gesture."

The report could force an investigating magistrate in charge of the case to downgrade the level of accusations against the officers. Any suggestion that police will not face serious criminal pursuits over the incident is likely to trigger further protests, as well as possible riots.

First support police

Presidential candidates, eager to move away from a series of scandals, quickly seized on the riots and controversy over Theo's arrest, with Le Pen standing out for her rapid defense of the police.

Politicians from the conservative Les Républicains (LR) party, which supports Fillon, called for "exemplary penalties" against any officers found guilty of misdeeds. Bruno Beschizza, the LR mayor of the town where the arrest happened, condemned what he called "extremely serious" acts.

Left-wing presidential contender Benoît Hamon denounced what he called "unacceptable violence" by the police, while Hollande paid a visit to Theo in hospital.

But Le Pen, who is seen reaching the final round of the election but being knocked out by either Fillon or Macron, took the opposite tack. "My principle is to first support the forces of police and gendarmes, except if their guilt is demonstrated," she told LCI TV.

"We don't know what the context of this arrest was, so going off images like this is fairly dangerous," she added.