France has named a second Frenchman in a video showing the killing of Syrian prisoners by Islamic State (IS) militants as Mickael Dos Santos, 22.
The Muslim convert comes from an eastern Paris suburb. The other French militant was named as Maxime Hauchard, a convert from Normandy.
In the same video, the severed head of US hostage Abdul-Rahman Kassig was displayed for the camera.
About 1,000 French jihadists are thought to have gone to Syria and Iraq.
French Prime Minister Manuel Valls said after a security meeting in Beauvais, north of Paris, that “close to 50” French citizens had died in Syria.
“Sadly, we are not surprised to learn that French citizens or residents of France are found at the heart of these cells and taking part in this barbarity,” he added.
