France, which has the largest Muslim population in Europe, is trying to contain the spread of a radical Islam hostile to Western influences. France has made similar anti-terrorism arrests before, only to release the suspects several days later without charges.
The prosecutor was careful not to draw direct links between Saturday's arrests and Mohamed Merah, a young Frenchman of Algerian descent who died in a shootout with police in March after the killings in the south of France. That attack terrorized the French Jewish community, which has since ramped up security in many parts of the country.
Merah had studied at an Islamist paramilitary camp in Pakistan and claimed ties to al-Qaida. Molins said officials did not believe the men arrested Saturday had trained abroad, but cautioned that the investigation was ongoing.