Heaps of rubbish were said to have been left at the site after 200 caravans descended on the central city of Clermont-Ferrand.
A traveller called Tom, from Scotland, told The Sun: "We're here to celebrate a friend's wedding."
Businesses said customers had been scared away while a restaurant boss whose toilets were used said: "They used us as a public convenience."
In February, another travellers' encampment caused controversy, when villagers in West Sussex were ordered to move their cars so police could escort an extra-wide mobile home to a site.
Residents found notices on their windscreens telling them that if they did not move their vehicles, they would be towed away at the owners' expense.
Police were escorting an extra-wide mobile home to a site that had been ruled illegal but was subject to a planning appeal.
Two caravans had been occupying the site at Three-Cornered Piece in nearby East Harting since 2009 after travellers from a village 15 miles away moved in on a Bank Holiday weekend.