PARIS -- French leaders from left to right urged a common front against far-rightist Jean-Marie Le Pen on Monday after he swept into the second round of the presidential election on a tide of protest votes, Reuters reported.

In a showing that shamed many French, sent shock waves through Europe and ended the career of third-placed Socialist Prime Minister Lionel Jospin, Le Pen came in second to President Jacques Chirac in Sunday's first round before a May 5 runoff.

Up to 10,000 protesters marched in Paris overnight shouting "Le Pen is a Fascist" while riot police fired teargas and drove back a crowd of hundreds of demonstrators who began throwing barriers in the capital's historic place De La Concorde.

Even the Euro was hit as Le Pen's anti-immigrant, anti-European Union policies spooked markets into trading the single currency slightly lower. French stocks also opened a fraction weaker, but overall market impact was seen limited.

Pollsters who failed to predict the rise of Le Pen in the first round forecast a second-round sweep for Chirac as key figures across the political spectrum acknowledged that backing the incumbent was the best way to keep Le Pen out of power.

"We shall do what we have to do because we are republicans and democrats," said Socialist Party General Secretary Francois Hollande, echoing other voices in his party, including Finance Minister Laurent Fabius.

Socialist chiefs were due to meet later in the morning to discuss whether the party would issue an outright endorsement of Chirac, 69, a figure despised by many left-wing voters.

Meanwhile, hundreds of students took to the streets in French cities Monday in a growing wave of spontaneous protests over far-right leader Jean-Marie Le Pen's success in the first round of the presidential election, AFP reported.

High school students marched out of classrooms in Lyon, Strasbourg, Reims, Rouen and Besancon to hold rallies, chanting slogans equating Le Pen to Hitler and calling his national front (FN) a Fascist organization.

Le Pen, a former paratrooper who ran on an anti-immigration, anti-EU and tough law-and-order ticket, beat Socialist Prime Minister Lionel Jospin to advance into the May 5 final round of the election with 17 percent of the vote behind incumbent President Jacques Chirac with 19.7 percent.

The crowds varied in size from 400 pupils in Strasbourg to 1,500 in Lyon and most taking part were too young to have voted in Sunday's poll or to vote in the May 5 decider.

"Mussolini: 1922. Hitler: 1933. Le Pen: Never," members of the rally in Strasbourg cried.

"You're out Le Pen -- the young are in the streets," others in Lyon shouted.

"F for 'Fascist', N for 'Nazi'," some screamed in reference to Le Pen's Party, while others carried a newspaper cover with Le Pen's photograph and "No" headlined across it.

The rallies threatened to get larger as demonstrations organized by university student and left-wing groups for later Monday got underway.

Much larger anti-Le Pen demonstrations took place overnight after Le Pen's second-place slot in Sunday's election became clear.

In Paris, around 15,000 marched along streets before being blocked by police barricades at the central place De La Concorde, next to the presidential palace and the French Parliament building.