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Thibault Camus, Associated Press
CGT Union leader Philippe Martinez, left, and FO union leader Jean-Claude Mailly lead a demonstration in Paris, Thursday, June 23, 2016. Unions are holding a short march Thursday around the Bastille plaza to protest government plans to make workweeks longer and layoffs easier. Similar protests against the legislation in recent months have degenerated into clashes between riot police and radicals.

PARIS — Tens of thousands of people marched in Paris on Thursday to protest planned labor reforms, gathering for a demonstration that authorities had initially considered banning due to the violence that has accompanied similar recent events.

No clashes were observed in the capital by mid-afternoon. But security was high and Paris police said they took at least 85 people into preventative detention, most of them for possession of objects that could be used as projectiles.

Unions organized the short march around the Bastille plaza to protest government plans to make workweeks longer and layoffs easier. Similar protests against the legislation in recent months have degenerated into clashes between riot police and radicals.

The authorities had initially threatened to ban Thursday's march, but the government agreed to let it proceed in a restricted area. Interior Minister Bernard Cazeneuve warned that "no violence will be tolerated."

The protesters marched quietly under a heavy sun along the 1.6 km (1-mile) permitted route, singing and shouting slogans like "no amendment, no negotiation: withdrawal, withdrawal of the law."

Unions estimated the crowd size at 60,000 people while police said the number was around 20,000.

Authorities had ordered the removal of benches and other objects from the streets to avoid potential damage to public property. Some boats docked in a port between the Seine River and the Bastille square were also removed ahead of time.

Police have said some union members participated in and cheered recent violence. But the head of the influential CGT union, Philippe Martinez, insisted on BFM television Thursday that, "We are not accomplices of the troublemakers. We condemn them firmly."

Other protests were organized Thursday in France's major cities to oppose the government's labor legislation, which is currently being debated in the Senate.