A “yellow vest” protester had four fingers blown off, reportedly by a stun grenade, as clashes erupted between anti-government demonstrators and riot police in Paris on Saturday.

The man was injured when he picked up a grenade thrown by police as they held off protesters who tried to force their way into the National Assembly, the lower house of the French parliament, witnesses said. Police could not confirm exactly how the injury happened but said the man had been taken to hospital.

Grisly video footage shows other protesters gathering around the injured man, aged about 30, and apparently trying to give him first aid as his hand spurted blood and he screamed in pain.

The incident came after an arson attack on the home of the National Assembly speaker on Friday night.

French police have often used stun grenades, each containing 25 grams of explosive, to disperse violent protesters since the weekly demonstrations began 13 weeks ago.

Two other protesters were injured in the face on Saturday, one when police fired a rubber “defence ball”, another controversial weapon banned in most other west European countries. Protesters kicked a police officer in the face during clashes on the Champs-Elysées and another officer was punched in the mouth.