Riot police in France used teargas to disperse protesters outside the Paris auto show during nationwide demonstrations over mounting job losses.
France's unemployment rate stands above 10% and the number of jobless has topped three million for the first time in 13 years, Reuters reports.
The CGT labour union, one of the two biggest in France, organised street rallies in the first nationwide protests since Socialist President Francois Hollande took power in May.
Police intervened after about 1,000 protesters including workers from a doomed PSA Peugeot Citroen plant attempted to break through a security cordon around the location of the car show on the edge of Paris, a Reuters reporter said.
Some protesters pelted the police with eggs and flour during the standoff.
CGT leader Bernard Thibault, who openly called for a vote to unseat former president Nicolas Sarkozy last May, said nothing was changing under Mr Hollande, who has promised to slash France's public deficit without killing growth or inflicting Greek-style cuts in spending on voters.
Thousands of people marched in Lyon and the southern port city of Marseille, according to police and union estimates, while other protests were planned in other cities.
As marchers hit the streets, President Hollande achieved majority backing from his own Socialist bloc in parliament on Tuesday for Europe's fiscal discipline treaty and was spared having to rely on opposition votes.