French authorities are investigating the case of an elderly female protester who suffered head injuries when police charged people defying a yellow vest protest ban in Nice.

The woman was waving a rainbow flag marked Peace and wearing a yellow vest when riot police carrying shields suddenly pushed toward the protesters on Saturday.

An Associated Press reporter saw her fall to the pavement, blood spilling from her head.

France Protests
Police officers stand by a yellow vest protester who collapsed on the ground during a protest in Nice (Claude Paris/AP)

Locals identified her as 73-year-old anti-globalisation activist Genevieve Legay.

Regional broadcaster France Bleu Azur reported on Sunday that she is in intensive care, and cited the Nice prosecutor as saying an investigation was opened.

French authorities banned protests in several areas Saturday to prevent a repeat of rioting that scarred Paris a week ago at yellow vest protests.