It was meant to be one of the “biggest civil disobedience events” ever, and spur on effective political action on climate change, but the protests in Paris on Sunday were muted and marred by tit-for-tat violence between masked youths and riot police.   

On the eve of the 2015 Paris Climate Conference (COP21), which optimists hope will save the planet from runaway global warming, dystopian scenes played out in the Place de la République square.

This report originally appeared on Al Jazeera.

Stand-off at Place de la République

Amid clouds of tear gas, youths in hoodies and bandanas threw rocks, bottles and mud at riot police, who charged and encircled demonstrators, sealing off streets leading into and out of the square.

By Sunday evening, almost 200 arrests had been made, prompting complaints that the authorities are cracking down not on terrorists and criminals, but on protesters and political dissent.

A threat to civil liberties? 

“We’re losing more and more of our rights,” says Margot Landaur, 51. “The young people here were pacifists. But what I saw today outraged me. I saw a girl about 20 years old, beaten by police for nothing. They hit her with their batons and injured her wrist. We helped take care of her, but she was in a state of shock. I think we’re heading in the direction of a kind of dictatorship.”

French authorities had banned Sunday’s demonstration after the November 13 attacks in Paris took the lives of 130 people. French authorities introduced a state of emergency now set to last at least three months with France’s Interior Minister Bernard Cazeneuve announcing that it could be renewed. Police warned that people gathering in large numbers would be vulnerable to further violence.

But demonstrators wonder why football matches, shops and the Champs Elysees Christmas market, also attracting thousands, were allowed to go ahead, while the Place de la Republique – now a makeshift shrine and memorial site for the victims – was encircled by riot police.

At least 200 arrests were made by Sunday

The rising tensions on Sunday have sparked angry accusations that the interior ministry is chipping away at civil liberties.

Over the past two weeks, almost 2,000 police raids have been carried out across the country – some of them even targeting environmental activists.

More than two dozen people involved in environmental campaigns are under house arrest until December 12, after the climate summit ends, sparking concerns that the terrorist attacks have provided authorities with a pretext to clamp down on far-left critics and political opponents.

Forty-three-year-old Loucero Mariani of the environmental campaign group Alternatiba in Rouen, based in northeastern Paris, refused to come out when police came banging on her door. She pretended to be out and didn’t make a sound until they had gone.

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Then, after answering a summons to appear at the police station, she was issued an order prohibiting involvement in the weekend’s COP21 protests.

“I went pale. It said, a violation of the conditions could mean six months in prison and 7,500 euros [$7,940] in fines. I couldn’t think of anything else. I don’t want to go to prison,” she said. Friends and colleagues, she adds, have also been subjected to police raids and house arrests.

“That means they’re associating us with the terrorists. We’re pacifists!”

Friends help man who was tear-gassed

With more than 140 world leaders and 40,000 participants expected in Paris this week, Cazeneuve has mobilised unprecedented levels of security forces, both from the army and the police, to monitor a wide array of possible security threats, including threats from environmentalists.

“Contrary to what might have been said, 26 orders for house arrests have by no means been given to pacifist environmental activists,” Cazeneuve said in a press conference on Sunday. “I am not confusing them with the people who have already participated in or contributed to several incidents of extreme violence.”