Protests have turned violent in France as at least 250,000 people rallied against a controversial new labour law.
A number of outbreaks of violence occurred in Paris
The worst violence was in Paris, where riot police fired rubber bullets and tear gas, and was reported in some of the other 80 cities holding rallies.
Protesters object to new two-year job contracts for under-26s which employers can break off without explanation.
President Jacques Chirac has appealed for talks, but says the new law is important to fight unemployment.
The march in Paris, which police said was attended by 30,000 but which organisers put at 120,000-strong, was mainly peaceful.
However, a group of about 300 masked protesters threw missiles at police, who responded with tear gas and rubber bullets.
A newspaper stand and a number of cars were set on fire and protesters at the symbolic Sorbonne University - where street protests shook France in 1968 - pelted police with stones and bottles and chanted slogans comparing them to the Nazi SS.
Clashes went on into the evening and the interior ministry said there had been about 150 arrests in Paris, along with at least 50 more elsewhere.
Two officers and a student were slightly hurt in scuffles in the northern Paris suburb of Raincy.
Six people were arrested and two officers hurt in Vitry-sur-Seine, south-east of Paris.
Police also fired tear gas in the north-western city of Rennes and a small number of injuries were reported in Nancy, Nantes and Montpellier.
Police put the number of protesters nationwide at 250,000 but organisers said it was double that.
Student leaders cited an opinion poll showing 68% support for the protests, while union bosses called for further street protests on Saturday.
Banners on Thursday read "Slave labour by the back door" and "If you take away our security, you'll pay".
"You can't live with a knife at your throat," one of the protesters, 21-year-old film student Sophie Cojan, said.
Police were under orders to be firm with troublemakers but to show general restraint, the interior ministry said.
Students fear the First Employment Contract (CPE), which passed into law last week, will erode job stability in a country where more than 20% of 18- to 25-year-olds are unemployed - more than twice the national average.
Mr Chirac has called for dialogue between ministers and labour leaders, but union officials say they will not enter into talks until the CPE is suspended.
The government of Prime Minister Dominique de Villepin proposed the law to help youths in the French suburbs who took to the streets last year, many unhappy with the lack of employment opportunities.
The BBC's Caroline Wyatt in Paris says the worry for the French government is that, as in May 1968, French students are expressing wider disenchantment with a government that is seen as remote and out of touch.