Rioting by youths in a Paris suburb has highlighted the discontent among sections of France’s immigrant population.
The BBC News website’s Henri Astier explores the sense of alienation felt by many French Muslims.
Many countries have ethnic and religious enclaves. But in France they cause particular alarm, for three reasons.
First, they are not supposed to exist in a nation that views itself as indivisible, and able to assimilate its diverse components.
Most French Muslims say Islam is compatible with French values
Separatism, the French are told, is a plague afflicting the Anglo-Saxon multicultural model.
The government bans official statistics based on ethnicity or religion. As a result, no one knows exactly how many Muslims live in the country – at least five million is the best guess.
Ghettos also threaten another tenet of French identity – secularism.
As the country celebrates the centenary of the separation of Church and State, Islam is seen as the biggest challenge to the country’s secular model in the past 100 years.
Thirdly, the worldwide rise of Islamic militancy strikes fear in the heart of a country that is home to Europe’s biggest Muslim community.
French police know that there is no shortage of potential jihadis in the country.
The assertiveness of French Islam is seen as a threat not just to the values of the republic, but to its very security.