In an especially strong response to the protest, the court handed down suspended prison sentences for each of the five and imposed fines and other penalties amounting to nearly 40,000 euros (nearly $47,200.)
Generation Identity, calling the decision "a scandal," said on its Facebook page that the five would immediately lodge an appeal, and asked for donations from sympathizers.
"The conviction of peaceful young citizens warning the French of the danger of the development of Islamism and massive immigration is particularly scandalous," the group's statement said, noting the terror attacks in Paris, Nice and elsewhere in France that have killed hundreds of people.
During the October 2012 demonstration, scores of people climbed atop a mosque under construction and unfurled banners. One read "Remember Charles Martel," who led the 732 battle to halt a Muslim advance in Europe. The group demanded a referendum on the building of mosques to cries of "In Poitiers, neither kebabs nor mosques."
Generation Identity, a French group with a presence in other European countries promotes the interests of what it regards as the continent's original inhabitants. The group claims that immigration by Muslims poses a danger to European culture and tradition.
The mosque occupation, filmed by a major French TV station that had been alerted in advance, was among Generation Identity's biggest publicity stunts. Last summer, the group chartered a ship and sent activists into the Mediterranean Sea to try to stop aid groups from rescuing migrants trying to get from Libya to Italy.
The five said in a statement during their October trial that they were simply "whistleblowers."
"By this decision, the justice of our country has clearly shown it has chosen its camp: that of Islamists ... against the defenders of France," Generation Identity said Thursday.
Four of the five received suspended one-year prison sentences and lost their civic rights for five years, including the right to vote, the court clerk's office said. The fifth received a suspended sentence and lost the right to run in elections.
All five must help pay an assortment of fines in damages and lawyers' fees that amount to nearly 40,000 euros. That includes a fine of 10,000 euros ($11,800) handed to Generation Identity.
This version has been corrected to show that financial penalties of nearly 40,000 euros converts to nearly $47,200.
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