— “I am not an anti-Semite,” French comedian Dieudonné M’bala M’bala says with a devilish grin near the start of his hit show at this city’s Théâtre de la Main d’Or.

Then come the Jew jokes.

In front of a packed house, he apes Alain Jakubowicz, a French Jewish leader who calls the humor of Dieudonné tantamount to hate speech. While the comedian skewers Jakubowicz, Stars of David glow on screen and, as the audience guffaws, a soundtrack plays evoking the trains to Nazi death camps. In various other skits, he belittles the Holocaust, then mocks it as a gross exaggeration.

In a country where Jewish leaders are decrying the worst climate of anti-Semitism in decades, Dieudonné, a longtime comedian and erstwhile politician whose attacks on Jews have grown progressively worse, is a sign of the times. French authorities issued an effective ban on his latest show in January for inciting hate. So he reworked the material to get back on stage — cutting, for instance, one joke lamenting the lack of modern-day gas chambers.

But the Afro-French comedian, whose stage name is simply Dieudonné, managed to salvage other bits, including his signature “quenelle” salute. Across Europe, the downward-pointing arm gesture that looks like an inverted Nazi salute has now gone so viral that it has popped up on army bases, in parliaments, at weddings and at professional soccer matches. Neo-Nazis have used it in front of synagogues and Holocaust memorials. Earlier this year, bands of Dieudonné supporters flashed it during a street protest in Paris while shouting, “Jews, out of France!”

“Dieudonné is getting millions of views on his videos on the Internet and is spreading his quenelle,” said Roger Cukierman, president of the Council for Jewish Institutions in France. “Something very worrying is happening in France. This is not a good time for Jews.”

Dieudonné was unavailable for comment, but his attorney, Sanjay Mirabeau, said the comedian was simply speaking truth to power.

“If the Portuguese were protected in France and had big influence, then he would protest the Portuguese,” Mirabeau said. “But as it is, there are others” who fit that description.

Jewish leaders say Dieudonné is a symptom of a larger problem. Here and across the region, they are talking of the rise of a “new anti-Semitism” based on the convergence of four main factors. They cite classic scapegoating amid hard economic times, the growing strength of far-right nationalists, a deteriorating relationship between black Europeans and Jews, and, importantly, increasing tensions with Europe’s surging Muslim population.

In Western Europe, no nation has seen the climate for Jews deteriorate more than France.

Anti-Semitism has ebbed and flowed here and throughout the region since the end of World War II, with outbreaks of violence and international terrorism — particularly in the 1980s and early 2000s — often linked to the Israeli-Palestinian conflict. But Jewish leaders here are now warning of a recent and fundamental shift tied to a spurt of homegrown anti-Semitism.

This month, authorities arrested Mehdi Nemmouche, a 29-year-old French national, and charged him with the May killings of four people inside a Jewish museum in Brussels. The attack was the deadliest act of anti-Semitism in Western Europe since a gunman killed seven people, including three children at a Jewish day school, in Toulouse in 2012. Nemmouche allegedly launched his attack after a tour of duty with rebels in Syria, prompting fears of additional violence to come as more of the hundreds of French nationals fighting there make their way home.

In a country that is home to the largest Jewish community in Europe, the first three months of the year saw reported acts of anti-Semitic violence in France skyrocket to 140 incidents, a 40 percent increase from the same period last year. This month, two young Jewish men were severely beaten on their way to synagogue in an eastern suburb of Paris.

Near the city’s Montmartre district, home to the Moulin Rouge and the Sacré-Coeur basilica, a woman verbally accosted a Jewish mother before rattling the carriage of her 6-month-old child and shouting, “dirty Jewess . . . you Jews have too many children,” according to a report filed by France’s National Bureau for Vigilance Against Anti-Semitism. Meanwhile, not far from the rolling vineyards of Bordeaux, stars of David were recently spray-painted on the homes of Jews.

A recent global survey by the New York-based Anti-Defamation League suggested that France now has the highest percentage in Western Europe — 37 percent — of people openly harboring anti-Semitic views. That compares with 8 percent in Britain, 20 percent in Italy and 27 percent in Germany. Jewish leaders chalk that up in part to growing radicalization of youths in France’s Muslim population — the largest in Europe — as well as outrage in the general public and French media over Israeli policy toward the Palestinians.

But it is also far more complex.

Anti-Semitism, Jewish activists fear, is becoming more socially acceptable. In May, for instance, the far-right National Front — a party long rooted in anti-Semitism but which sought to portray itself as reformed — came in first in elections here for the European Parliament, winning a whopping 25 percent of the national vote. Yet last week, its patriarch, Jean-Marie Le Pen, suggested just how unreformed a segment of the party remains. In a video posted on the party’s Web site, he suggested that a Jewish folk singer should be thrown into an oven.

Le Pen’s daughter and current party leader, Marine Le Pen, offered a rare rebuke of her father’s words and ordered footage of the comments removed from the party’s Web site. The elder Le Pen’s musings were nevertheless seen as unsurprising within a party whose older members have long harkened back to the days of Vichy France, the Nazi collaborators who allowed tens of thousands of French Jews to go to their deaths.

“I walked into my kosher sandwich shop the other day and the owner asked me, ‘Is it time to leave? Are we Nazi Germany yet?’ ” said Shimon Samuels, the Paris-based international director of the Simon Wiesenthal Center. “We’ve got the National Front in first place. We’ve got Dieudonné, spreading his hate. So I told him, ‘Well, do you really want to be the last to go?’ ”

Indeed, French migration to Israel in 2013 jumped to 3,200 people, up 64 percent from 2012. A huge uptick in departures this year has Jewish leaders here predicting that at least 5,000 French Jews will leave in 2014.

“We’ve been thinking about moving for a long time, but the climate was not as dangerous as it is now,” said Alain, 30, a medical equipment specialist who is moving to Israel in July with his wife and three children. He declined to give his last name out of fear for his family’s security.

Sitting at his modest dining-room table in eastern Paris, a set of moving boxes in the next room, he added: “It bothers me because this is not normal; this is not how I remember France when I was growing up.”

Two weeks ago, Alain said, he woke up to find his 13-year-old daughter, Michele, crying. After a recent attack on two Jewish boys not far from her school, she said she was too afraid to join her regular car pool. Instead, she demanded that he take her to school and pick her up, standing guard as she entered and exited each day. He has moved his work schedule around to accommodate her request.

Asked what she was scared of, Michele, an elegant French teenager in a fashionable black skirt and white T-shirt, looked down and said: “I’m afraid that what happened in Toulouse will happen at my school, too. . . . I hear what people say about Jews. And I am scared.”

Enter Dieudonné.

Born to a father from Cameroon and a white French mother, Dieudonné, ironically, rose to stardom in the 1990s as part of a duo act with Élie Semoun, a Jewish comedian. But the two grew estranged as Dieudonné’s humor became indistinguishable from anti-Semitic diatribe.

In the 2000s, he wooed the far right and the far left as his campaign against Zionism made him an unlikely symbol for both. Throughout the 2000s, he was repeatedly fined for making a variety of anti-Semitic statements, including his description of Holocaust commemorations as “memorial porn.”

Blacklisted from mainstream TV shows and radio, he nevertheless thrives, with a cultlike following on stage and via the Internet, where his satirical videos stand out among a rash of new anti-Semitic Web sites in France. As he has become less mainstream, he has traded larger venues for relatively smaller theater spaces where he is filling seats with fans across racial, political and socioeconomic spectrums.

Dieudonné is an equal-opportunity offender. His act is a study in provocation, targeting not only Jews but also gays and mainstream politicians. Yet — as evidenced by the T-shirts bearing the quenelle salute on sale at his shows — he tends to reserve his toughest punch lines for Jews.

Over the past year, observers say, his depictions have sharply worsened. His act became so offensive that the French government in January took the rare step of encouraging local jurisdictions to bar his performances. The move forced him to tone down his material, largely by deploying inference and shorthand to get his point across.

Virgile Demoustier contributed to this report.