Demonstrators opposed to a new jobs law swarmed parts of downtown Paris on Tuesday, throwing stones, tearing down street signs and ripping up park benches. Riot police, firing tear gas canisters and making several charges, carried away protesters in handcuffs.

Police said at least 1 million people poured into the streets around the country in the latest protests against the law, which makes it easier to fire young workers. Organizers said 3 million people marched.

A nationwide strike shut down the Eiffel Tower and snarled air and rail travel for the second time in a week while students barricaded themselves in schools.

It was the second time in a week that unions and student groups had succeeded in mobilizing such numbers. The largest march, in Paris, drew at least 80,000 people, while 935,000 marched in other parts of the country, police said.

Organizers put the figure in the capital at 700,000.

Violence erupted at the end of the largest protest on the fringes of working-class neighborhoods, with youths in Place d'Italie pelting police with stones, fighting and using metal bars to break up chunks of pavement that they hurled at helmeted riot officers.

One young woman twirled flaming batons. The sounds of blowing whistles were heard throughout the plaza.

Officers carrying batons and shields charged several times, making arrests.

Protesters have mounted ever-larger demonstrations for two months against the law. But President Jacques Chirac signed it anyway Sunday, saying it will help France keep pace with the global economy.

He offered modifications, but students and unions rejected them, saying they want the law withdrawn, not softened.

"What Chirac has done is not enough," said Rebecca Konforti, 18, who was among a group of students who jammed tables against the door of their high school in southern Paris to block entry. "They're not really concessions. He just did it to calm the students."

By midday, police said at least 100,000 people had hit French streets, including buoyant students parading through Marseille under a sunny southern sky and major marches from Nantes in the west to Saint-Etienne in the southeast. Protests even reached the French Indian Ocean island of Reunion, where 2,000 people marched.

Some 60 students lobbed eggs and other objects at police in the northern city of Lille, and at least one person was detained.

Organizers, who said the turnout was in the hundreds of thousands, hoped it would exceed the 1 million who marched last week. The afternoon march in Paris promised to be the biggest, and the city deployed 4,000 police to avert violence that marred previous protests.

Police actively looked to thwart troublemakers. At Paris' Saint-Lazare station, riot officers with weapons and a police dog pulled over train travelers disembarking from the suburbs, searching their bags and checking identities.

Tourists, meanwhile, stood bewildered before closed gates at the Eiffel Tower. Parisian commuters flattened themselves onto limited subway trains. Garbage bins in some Paris neighborhoods stood overflowing and uncollected by striking sanitation workers.

Irish budget airline Ryanair canceled all its flights in and out of France.

The strike appeared weaker, however, than last week's action. Signs of a possible breakthrough began to emerge as labor leaders suggested they could hold talks with lawmakers after Tuesday's demonstrations.

Prime Minister Dominique de Villepin devised the disputed "first job contract" as a bid to boost the economy and stem chronic youth unemployment. He maintains it would encourage hiring by allowing employers to fire workers under 26 during their first two years on a job without giving a reason.

The measure is meant to cut a 22 percent unemployment rate among youths that reaches 50 percent in some poor, heavily immigrant neighborhoods. Villepin has cited the national statistics agency as saying it would create up to 80,000 new jobs at zero cost to the state.

Critics say it threatens France's hallmark labor protections, and the crisis has severely damaged Villepin's political reputation.

Chirac stepped in Friday to order two major modifications — reducing a trial period of two years to one year and forcing employers to explain any firings — in hopes of defusing the crisis. In so doing, he dealt a blow to Villepin, his one-time top aide and apparent choice as successor next year.

In an apparent first in France, Chirac signed the original measure into law this weekend, as promised, but also effectively suspended it with an order that it not be applied. The 73-year-old president's legal sleight of hand kept the law alive while a new version is in the works.

Now that the law has been signed, protesters have less maneuvering room. The government appeared to be hoping that protests would die down after Tuesday's big event and was looking to possible talks between more moderate unions and lawmakers led by Interior Minister Nicolas Sarkozy.

Sarkozy, a leading presidential hopeful, is the only senior government official unscathed by the crisis.

The head of the governing UMP party's bloc in parliament, Bernard Accoyer, told reporters he had invited labor leaders to talks.

Two labor leaders — CFDT union chief Francois Chereque and CGT union chief Bernard Thibault — suggested they would attend. But both said they hoped the law eventually would be rejected.