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PARIS (Reuters) - French riot police clashed with youths in central Paris on Thursday when a demonstration against far right leader presidential candidate Marine Le Pen and her centrist rival Emmanuel Macron turned violent.

Police replied with teargas as hooded youths threw bottles on the sidelines of a march by about 500 hundred high school students.

Police also used teargas against protesters in the western city of Rennes where nearly 2,000 high school and university students, and far-left activists, held a demonstration, a Reuters correspondent there reported.

In Paris, protesting students blocked the entrances, or staged election-related demonstrations, at about 20 high schools earlier on Thursday after student unions urged them to turn out.

Students have been holding “neither Le Pen, neither Macron” protests at high schools since the two qualified on Sunday for a May 7 runoff vote in France’s two-stage presidential election.

“We are calling for action against far right candidate Marine Le Pen and the candidate of high finance, Emmanuel Macron,” said UNL-SD student union leader Giuseppe Aviges, alluding to Macron’s past as an investment banker.