French riot police arrested 27 people during overnight clashes with dozens of youths in central Paris, following a day of protest marches over labor law reforms that turned violent. Some opposition lawmakers and police union representatives urged a government crackdown on demonstrations and said it was time for an outright ban on the daily, mostly peaceful, youth protests at the site of Thursday night's skirmishes.The latest trouble erupted when police moved in to clear a group of about 150 youths from the Place de la Republique square in the early hours of the morning. Cars were set ablaze and lumps of concrete and cobblestones hurled at officers. Twenty-four of the 27 arrested were held in custody, police said."These are largely people coming looking for a fight," Interior Ministry spokesman Pierre-Henry Brandet said. The unrest comes at a time police forces and soldiers are working overtime to ensure security in the wake of last November's deadly militant attacks on the capital.Tens of thousands of people took to the streets country-wide on Thursday to protest against labour law reforms aimed at making hiring and firing easier. Violent clashes broke out on the fringes of demonstrations in several cities. Interior Minister Bernard Cazeneuve said 214 arrests were made in all. Seventy-eight police were injured, with one in a serious condition after a skull-cracking blow from a paving block. Paris police prefect Michel Cadot has said organized groups were behind the protest violence, which has mushroomed despite the state of emergency imposed after November's attacks.Some police union representatives have called on police chiefs to issue fewer protest permits. Nicolas Comte of the police union SGP police-FO said it was time to ban the Place de la Republique protest known as "Nuit Debout" - which roughly translates as "Up all night" - arguing gangs of hardcore troublemakers were hijacking the movement.The French government has condemned the violence but, with just a year to national elections, has appeared keen to avoid the curfews it has the power to impose under the state of emergency. Cazeneuve said almost 1,000 people had been arrested since protests started in March and dismissed calls for an all-out crackdown. "State authority does not mean you abandon the rule of law," the minister said.