MARSEILLE, France — Though it was almost midnight, streets were full of Muslim families taking a stroll after breaking the Ramadan fast with a late dinner. As two policemen drove by a storefront recycled as the Grand Sunna Mosque, they noticed a woman wearing flowing black robes and a full-face veil.

The policemen alighted from their patrol car and challenged the woman on her veil, which has been illegal in France since April 2011. After an angry exchange, police said later, the woman shouted that she would not abide by the anti-veil law, and a youth told police they had no business patrolling the neighborhood and accosting its predominantly Muslim residents.

The confrontation quickly escalated into a shoving match, with several dozen young bystanders joining in and carloads of police reinforcements speeding in to lend a hand. Before long it erupted into what was described in the National Assembly in Paris as a riot, during which a female police officer was bitten on the arm and two of her male colleagues were bashed and bruised.

The sudden clash, which took place July 24 in Marseille, was the most serious instance of resistance to the veil ban during its 16 months of enforcement, according to police. Although it subsided almost as quickly as it flared, the outburst focused national attention on simmering resentment over the ban among France’s most militant and tradition-minded Muslims.

Although complaining about what they call ‘‘stigmatization,’’ France’s mainstream Muslim organizations have recognized the ban as the law of the land and called on followers to heed it. Most have gone along. But the makeshift Grand Sunna Mosque, police noted, has acquired a reputation as a home for the city’s more radical preachers, over whom the moderate national groups have little sway and whose followers are eager to affirm their Muslim identity.

‘‘For young militants, this ban upsets them,’’ said Nassera Benmarnia, who heads the local Muslim Family Union. ‘‘But most people just want to be left alone.’’

A middle-aged man behind the counter of a busy shawarma shop, with recordings of plaintive Koranic verse playing in the background, agreed. Between handing out sandwiches, he explained that most French Muslims see no need for a full-face veil, but that for some, it is the response to a ‘‘Muslim taboo,’’ forbidding the display of a woman’s beauty outside her family.

France, which has Europe’s largest Muslim population, is the only country with a national ban against full-face veils, usually called a niqab. The law has been supported across the political spectrum in Paris. But the State Department, in an annual report on religious freedom, recently criticized it for the second time as an infringement on freedom of choice.

Belgium’s lower house of Parliament has passed similar anti-veil legislation, and the government hopes to get the law validated soon in the Senate. The Dutch government has said it also would seek to impose a ban next year. Meanwhile, some Belgian cities, including Brussels, the capital, have already enacted bans at the municipal level.

The bans reflect Western Europe’s unease at growing Muslim minorities, which sometimes are numerous enough to retain their own dress and customs in what can appear to be a challenge to the continent’s Christian roots and traditions. The chafing has intensified during Europe’s economic crisis.

The French Interior Ministry said in April, on the ban’s first anniversary, that 354 women had been challenged by police for wearing full-face veils and 299 were given citations similar to traffic tickets. A ministry spokesman, Pierre-Henri Brandet, told reporters the French law was being applied ‘‘in serenity’’ but did not explain how many of the women were forced to pay fines or attend civics classes as prescribed by the law.