PARIS, Oct 24 — French police started firing tear gas at protesters Saturday as they stepped up security in major cities aiming to prevent a repeat of rioting a week ago, on a day of fresh nationwide demonstrations over the high cost of living.

Police in the southeast city of Lyon fired tear gas to disperse some 150 protesters near the city centre — where demonstrations had been banned — when they briefly tried to block a road, an AFP journalist saw.

“The police are really mobile... They come and disperse marches before they even form,” said a 21-year-old student who had turned up to protest, speaking on condition of anonymity.

Elsewhere, authorities and rattled shopkeepers geared up for potential new street violence.