PARIS — The French police have arrested a prominent leader of the Yellow Vest movement for a second time, in a clear sign that the government is following through on a pledge to crack down on the protests that have shaken France for much of the past six weeks.



Éric Drouet, a 33-year-old truck driver from the Paris exurbs who was one of the original organizers of the movement, was arrested Wednesday night in Paris for what the authorities said was “organizing an undeclared demonstration.” On Thursday, he was released pending a trial.

“We’ve got to shock public opinion,” Mr. Drouet said in a video on Facebook before going to the Place de le Concorde on Wednesday and placing candles for the movement’s wounded. He called for “action” on the Champs-Élysées, where several dozen Yellow Vests were waiting for him that evening outside a McDonald’s restaurant.

Instead, shortly after 9 p.m., Mr. Drouet was hustled into a police van by riot police officers.

French law requires the organizers of street demonstrations to inform the local authorities about their plans. Violations can bring six months in jail and a fine of 7,500 euros, about $8,500.