French police on Wednesday banned a Paris protest march 24 hours before labor unions were set to lead tens of thousands into the streets, setting the scene for a potentially violent standoff if the demonstration goes ahead. Left-wingers condemned what they said was the first ban of a union-backed protest since the early 1960s when protesters died in clashes with police during a march banned by the Paris police prefect of the time, Maurice Papon. The decision followed a breakdown in negotiations between the government and the leaders of the CGT and Force Ouvriere (FO) unions, who refused proposals that they hold a rally in a large square but not march through the streets of the capital. Violence on the fringes of protests has stretched a police force already challenged by the demands of a state of emergency in place since Islamist militant attacks on Paris last November. "After close examination, these alternative proposals address neither the security needs of people and property, nor the demands on police resources given the terrorist threat," a police department statement said. "Under these conditions the Prefect of Police believes he has no choice but to ban the demonstration." Interior Minister Bernard Cazeneuve set the stage for a ban this week, saying violence at the rallies had got out of hand at a time when riot police were battling to contain fan violence during the Euro 2016 soccer tournament that France is hosting. But in a sign that efforts were still being made to find a way out of the standoff, Cazeneuve met Philippe Martinez and Jean-Claude Mailly, respective leaders of the hard-line CGT and FO union at their request. "It's better to talk with one another than speak through statements," Martinez told reporters after the meeting. Asked whether he was confident a compromise could be found, Mailly said he was "neither optimistic, nor pessimistic." Other union officials took a tougher stance. "This is a declaration of war," Benjamin Amar, a CGT official, told BFM TV. "We're going to go ahead and protest tomorrow in any case." The unions have been protesting since early March against planned reforms to make hiring and firing easier. Under French law, protesters risk up to six months in jail if they defy a ban. The ban means police may end up having to deploy in numbers in any case to enforce the government order if unions ignore it. — Reuters