Paris ? Police used tear gas and water cannon against rampaging youth in Lyon on Thursday while the French government showed its muscle in parliament, short-circuiting tense Senate debate on a bill raising the retirement age to 62.

A student shouts slogans during a demonstration Thursday in Paris. On her cheek reads: No to the reform.

Despite growing pressure, President Nicolas Sarkozy held firm on a measure he says is crucial to the future of France, heightening the standoff with labor unions that see retirement at 60 as a hard-earned right.

Defiant unions announced two more days of protest, one on Nov. 6 — long after the bill is likely to become law. The bold action suggested that opponents believe they have the power to force the government’s hand.

“The government bears full and complete responsibility for the continued mobilization, given its intransigent attitude, its failure to listen and its repeated provocations,” said the statement signed by six unions.

Weeks of protests have left at least a quarter of the nation’s gas stations on empty, blocked hundreds of ships at the Mediterranean port of Marseille and even forced Lady Gaga to cancel Paris concerts.

Violence on the margins of student protests have added a new dimension to the volatile mix.

A march in Paris by at least 4,000 students was peaceful, but new violence broke out in Lyon, where police used water cannon and tear gas to hold back rampaging youths hurling bottles and overturning at least one car.

“It is not troublemakers who will have the last word in a democracy,” Sarkozy told local officials in central France, promising to find and punish rioters. He accused strikers of “taking the economy, businesses, daily life hostage.”