Chaos erupted on the streets of Paris as a May Day workers’ march saw riots break-out in protest against Marine Le Pen.
Fighting broke out in central Paris during a rally held close to the Place de la Bastille, where protestors shouted ‘Fascists out!’.
They were furious that Ms Le Pen, 48, has got through to the second round of the election to choose a new head of state.
Six French police officers were injured by Molotov cocktails with one badly hurt by a firebomb that exploded on top of his helmet which resulted in flames engulfing his entire body.
A police source said: “Around one hundred hooded protestors got as close as they could to police lines, and then one or two threw Molotov Cocktails.
“One officer suffered serious burns to the face just after 3pm. He was rushed to hospital. He is in a bad way, but his condition is not life threatening. Another officer suffered serious hand wounds, while others were less badly hurt. There were five arrests in all.”
Ms Le Pen will go head-to-head against independent favourite Emmanuel Macron, 39, on Sunday.
“She represents racism and hatred, that’s why we’re opposing her,” said one left-wing activist Nicole, aged 22.