Paris, Jan 18 (IANS): Former French Prime Minister Manuel Valls was slapped by a young man during a campaign visit to northern France as a candidate for the left primary of the presidential election, media reports said on Wednesday.

A video broadcast showed Valls exiting from the Lamballe city hall on Tuesday and shaking hands with a group of people while a youth among them caught him a light slap in the face before being seized by security guards, Xinhua news agency reported.

The 19-year-old man was arrested and placed into custody on charges of "violence against a person having public authority".

Speaking to reporters shortly after the incident, Valls said: "I have never been afraid of having contact with French people whatever their opinions. Democracy can never mean violence."

Valls has been the polls' favourite to win the left ticket and challenge conservative candidate Francois Fillon and Marine Le Pen, head of far-right National Front party.

However, he was losing momentum after two televised debates that offered a boost to former Economy Minister Arnaud Montebourg, days ahead the competition's first round.