An increasingly violent wave of anti-Semitic words and acts in France threatens the very existence of Jewish communities there, one human rights advocacy group warned in a new report.

The attacks are “a harbinger of societal breakdown,” said Susan Corke of Human Rights First. “Left unchecked, antisemitism leads to the persecution of other minorities, and to an overall increase in repression and intolerance.”

Reported anti-Semitic hate crimes in France have more than doubled from 423 in 2014 to 851 in 2015, according to numbers cited in the report “Breaking the Cycle of Violence: Countering Antisemitism and Extremism in France” released Jan. 7 by the group Human Rights First and authored by Corke.

“These incidents are increasingly violent,” the report stated.

Jews only comprise one percent of France's population, but over half of the reported hate crimes in France were anti-Semitic in 2014. And anti-Semitism was almost exclusively responsible for the 30 percent increase in “racist acts” between 2013 and 2014, according to numbers cited in the report from the French Ministry of the Interior.

And over 80 percent of incidents are not reported, according to one European Union survey.

Most incidents are verbal threats and insults made against Jews, but they also include physical assaults as well as graffiti and vandalism against Jewish stores and synagogues.

The most notable acts of violence in recent years were a 2012 shooting at a Jewish school in Toulouse that killed four and was linked to Islamic extremism and anti-Semitism, and the shooting of four hostages at a kosher supermarket in Paris in January of 2015.

Jews have a long history in France having settled there since the 6th century and enjoying citizenship since the time of Napoleon. Yet today’s hate crimes seem to have a chilling effect.

The number of French Jews emigrating to Israel spiked to 3,295 in 2013 and more than doubled to 7,230 in 2014, according to the Jewish Agency for Israel which monitors the numbers of Jewish immigrants from France. Previously the annual figure was around one to two thousand.

Jews who stay in France are more afraid to wear public symbols and identifications of their faith. Parents are transferring their children from public schools to private schools to escape discrimination and harassment, and many teachers have reported critical or outright anti-Semitic responses from students when they teach about the Holocaust or Jewish history.

The commissioner of the U.S. Commission on International Religious Freedom, Dr. Katrina Lantos Swett, told CNA/EWTN News last March of the fear in the Jewish communities that she witnessed during a visit to France. Many Jewish parents “don’t see a Jewish future” for their children there, she said. The government has stationed security outside of Jewish buildings and synagogues to protect them from vandalism and violence.

The decline of the situation is largely due to two major factors: the rise of the far-right National Front political party, and the resentment of disenfranchised immigrant and minority groups, the report said.

The National Front has soared into the mainstream of French politics recently, winning first place in the 2014 elections and the first round of the 2015 regional elections in November. The party “rallies its supporters around animosity towards Muslims, Roma, foreigners, and migrants,” the report stated, and although leaders have tried to cleanse it of anti-Semitic and Holocaust-denying rhetoric, its platform “still contains positions on ritual animal slaughter and public subsidies that are discriminatory against Jews as well as Muslims.”

Many members of its base still hold anti-Semitic views. In two French surveys — a 2014 report on tolerance submitted to the French government, and a report by a French think tank — over half of the respondents who supported the National Front espoused anti-Semitism.

Outside of the party, many immigrants and descendants of immigrants have been unable to assimilate into the societal mainstream and may harbor resentment toward Jews who they mistakenly see as controlling wealth and power.

“French Muslims, immigrants, and French citizens of Middle Eastern, North African, or Sub-Saharan African heritage, especially those living and attending school in marginalized areas, experience prejudice and suffer from hate crimes as well as official and private discrimination,” the report noted.

Many young people in these communities suffer a lack of education and social mobility and are exposed to extremist views on the internet that “bombard” them with anti-Semitism.

Some of the most common anti-Semitic beliefs are that the Jews control too much power or too much wealth, the report noted, and some of the other less common attitudes are that the Jews “use the Holocaust to their advantage,” and are more loyal to the state of Israel than France.

The discrimination is concentrated more among the elderly, poor, less educated, and more religious, the report added, and is more likely to occur during heightened Israeli-Palestinian conflict and right after terror attacks or well-publicized anti-Semitic hate crimes.

However, even some French “observant Catholics” have shown anti-Semitic attitudes, according to a 2014 survey by a French think tank FONDAPOL cited in the report. Twenty-two percent of practicing Catholics surveyed said there too many Jews in France, while 16 percent of all those surveyed answered that way.

According to the report, the U.S. must speak out against the rise of anti-Semitism but should also refrain from aggravating the marginalization that many groups currently experience in France. In part, “official statements should avoid fueling a ‘clash of civilizations’ narrative between Jewish and Muslim communities and instead urge tolerance and inclusion,” the report recommended.