A photograph of Marine Le Pen's deputy dining at a North African restaurant with other National Front officials has horrified supporters, who found their "unpatriotic" culinary choice hard to swallow.
The row, dubbed #CouscousGate on social networks, highlights a growing rift within the far-right anti-immigration party, which could further undermine Le Pen's leadership four months after her defeat in the presidential election.
The picture of Florian Philippot, the party's vice-president and MEP, with National Front colleagues at a restaurant in Strasbourg was posted on Twitter by Kelly Betesh, a party activist.
It infuriated many party loyalists, especially those who oppose efforts by Philippot, who is openly gay, to reform the party and distance it from its anti-Semitic past. One tweet called for Philippot, 35, and his companions to be expelled.
"When you've been thrown out of the National Front, we'll eat a good choucroute [a French version of the German dish sauerkraut and a Strasbourg speciality] to celebrate, not a couscous."