PARIS, March 21 (Xinhua) -- Some 50 protesters turned violent late Tuesday, hurling paving stones at police who beat back with teargas outside the Sorbonne University in the left bank quarter in Paris.

    Earlier in the day, thousands of college students and high school students protested in a manifestation against the First Employment Contract (CPE), a legislation sponsored by French PrimeMinister Dominique de Villepin.

    According to the French Education Ministry, out of the 84 universities across the country, 15 were completely shut down Tuesday and a further 41 disturbed.

    The FIDL union of lycee (French high school) students said some25 percent of the country's 4,370 high schools have been hit till Tuesday by total or partial closures by the protest campaign against the CPE.

    As students were preparing another day of national strike on Thursday after three days of national strikes over the last two weeks that implying hundreds of thousands of students, Villepin vowed not to give in.

    He reiterated Tuesday evening that he would accept neither withdrawal, nor suspension nor any distortion of his legislation aimed at making working practices more flexible to lower unemployment but seen by critics as a threat to job security.

    In his address before French deputies and senators of his UMP parliamentary party on Tuesday, Villepin said "three things are impossible: one is withdrawal, that would mean capitulating beforethe logic of ultimatums and preconditions. Our voters don't want that. Second is suspension. Quite simply that is against our constitution. Third distortion of our project: to lose the balanceof the project would deprive us of any chance of success."

    He also insisted that the two-year trial period would not be changed and indirectly criticized the Socialist opposition for being behind its criticism to hide "its lack of ideas, the absenceof any plan or vision".

    Aiming at solving unemployment and removing the fear that they could be stuck with a costly long-term commitment if the worker proves unsuitable or if economic conditions deteriorate, the French parliament adopted 10 days ago the CPE, which suggests employers to hire young people under 26 under an open-ended two-year contract that can be terminated without explanation.

    Opponents said the law infringes workers' rights, making it harder for young people to get long-term employment.

    But the French prime minister said that the CPE was "an essential tool for freeing up the labor market and creating jobs".

    An LH2 poll published by French left-wing daily Liberation newspaper on Monday showed that 35 percent of the public want the CPE scrapped and 38 percent said it should be modified, and 71 percent agreed with the statement that France was in a "profound social crisis which will grow in the weeks ahead".

    France has one of Europe's highest youth unemployment rates, with 23 percent of all young jobseekers out of work and some 40 percent in some of the poor high-immigration city suburbs. Enditem