Paris ? Students clashed with police and activists rampaged through a McDonald’s restaurant and torched the entrance to a Gap store in the capital Saturday as demonstrations against a government plan to loosen job protections spread across France.

The protests against the law, which drew some 500,000 people in cities across the country, were the biggest show yet of escalating anger that is testing the strength of the conservative government before elections next year.

The rallies and marches were largely peaceful, but police fired tear gas during confrontations with stone-throwing youths in Paris. Four officers and 12 protesters were injured, and police arrested at least 59 people, Paris officials said.

With commerce snarled in some cities, people asked whether Prime Minister Dominique de Villepin would stand firm on implementing the change that he says is needed to encourage hiring and cut unemployment. The usually outspoken leader was silent Saturday.

Protests reached every corner of France, with organizers citing 160 marches from the small provincial town of Rochefort in the southwest to the major city of Lyon in the southeast.

In Marseille, extreme leftist youths climbed the facade of City Hall, replacing a French flag with a banner reading “Anticapitalism.” Police used tear gas to disperse them and made several arrests.

French riot police officers run past a burning car during clashes following a demonstration in Paris against the First

Police also fired tear gas at a protest in Clermont-Ferrand, a central city where 10,000 people marched and about 100 youths threw beer cans and other projectiles at a building.

The Paris protest march was the biggest, attracting some 80,000 people, according to police. Organizers put the number at 300,000.

Some demonstrators became violent as the march ended. Youths set a car on fire, smashing a shop window, trashing a bus stop and throwing stones, golf balls and other objects at police. Police responded with tear gas during skirmishes that lasted several hours.

About a dozen protesters stormed a McDonald’s near Place de la Nation in eastern Paris, where the march ended. They broke windows and punched in the wall of a takeout window before fleeing ahead of police, leaving customers and employees stunned and shaken.

Later in an apparent effort to set fire to a police van serving as a blockade, protesters instead torched the entrance of a Gap store near the Sorbonne.

Widespread discontent with the government has crystalized around a new type of job contract that Villepin says will alleviate France’s sky-high youth unemployment by getting companies to risk hiring young workers.

Critics say the contract abolishes labor protections crucial to the social fabric.

“Aren’t we the future of France?” asked Aurelie Silan, a 20-year-old student who joined a river of protesters crawling through Paris.

The law would allow businesses to fire young workers in the first two years on a job without giving a reason, removing them from protections that restrict layoffs of regular employees.

The government says companies are reluctant to add employees now because it is hard to let them go if business conditions worsen. Villepin says making it easier for businesses to hire and fire young people would help France compete in a globalizing world economy.

Youth joblessness stands at 23 percent nationwide, and 50 percent among impoverished young people. The lack of work was blamed in part for the riots that shook France’s depressed suburbs during the fall.