In my opinion this is nearer the point than "extreme right".
There is an international anarchist alliance active in Europe.
Planned peaceful demonstrations in France over the past few years have been infiltrated by "casseurs". Usually young men dressed in black overalls, wearing masks and usually carrying back packs full of projectiles.
These people come into Paris from Belgium, Germany etc and are not identifiable until they start wrecking.
It is suspected that they are supported by the "far left".