PARIS — Rallies across France this week have shown the strength of French Jews as they battle a recent surge in anti-Semitism.

But Sunday's rallies have also exposed fissures among Jewish groups.

The largest rally occurred in Paris, with an estimated 50,000 people, while smaller rallies were held in Marseille, Lyon and Toulouse.

The rallies came as a wave of anti-Semitic attacks not seen here since World War II continued unabated.

President Jacques Chirac on Tuesday made the first visit by a French head of state to Paris' Grand Mosque in 76 years to denounce the spate of attacks on Jewish sites and call for unity between French Jews and Muslims.

Synagogues, schools and cemeteries around the country have been targeted, often with firebombs, in the last two weeks. In the most serious case, a Marseille synagogue was burned to the ground on March 31.

"I want to reiterate here with you how much these odious attacks aren't worthy of our country," Chirac said. "I want to say again, with force, that external conflicts mustn't pit French against French on our soil."

In the latest episode, a gasoline bomb was lobbed Tuesday night at a synagogue in the Paris suburb of Garges-les-Gonesse but did not explode, local officials said. The same synagogue was targeted over the weekend.

Thirty-nine people have been detained in the wave of attacks, but only 10 remain in jail for their alleged roles, said police spokesman Alain Tourre.

In a stormy meeting on April 2, some Jewish communal officials sharply criticized Jewish leader Roger Cukierman for promoting Sunday's Paris rally more as a "defense of Israel and its government" than a denunciation of French anti-Semitism.

Cukierman, the president of an umbrella organization for secular French Jews, placated some of these critics by redefining the demonstration as a show of support for the "Israeli people," rather than for the government.

But several Jewish organizations still felt the need to put their own spin on the protest.

The Union of French Jewish Students and the League Against Racism and Anti-Semitism issued their own call for "a republican mobilization against anti-Semitism,' and a French Jewish pacifist group, Friends of Shalom Achshav, organized a 'parallel demonstration' in support of the formula of two nations, two states for peace."

These differences erupted during the Paris demonstration when young members of the radical groups Betar and the Jewish Defense League assaulted peace protesters as they attempted to join the larger demonstration.

Indicative of the mounting anger among the younger generation of French Jews, who are the most exposed to the everyday realities of anti-Jewish aggression, the ranks of these organizations have swelled in the past few weeks.

In Paris, several hundred members of Betar and the JDL, clad in white armbands and yellow T-shirts, circulated around Bastille Square, roughly preventing photographers from taking pictures and once fighting with a group of Arab youths attempting to display a Palestinian flag.

In one incident, a youth from one of the Jewish groups stabbed a police officer in the abdomen with a knife.

Members of these organizations also clashed with a large group of Arab youths in Marseille who attempted to menace protesters. Before riot police could intervene, one Jewish youth sustained a cut from a knife.

While the violent actions and the pro-Sharon sentiments of these groups received a great deal of attention in the French media, the majority of demonstration signs articulated cries for peace in Israel and France.

Cukierman was quick to denounce the violence as 'extremist' following the rally, but nobody in the community is dismissing their significance.

To some observers, they demonstrate that despite joining together in perhaps the largest mobilization of Jews in French history, the French Jewish community seems to be growing more and more divided over the policies of the Sharon government.

"Until now, when French Jews would take the streets, they would do it for themselves, but also to defend democratic and ethical values since they were inseparable from their own values," said Olivier Guland, the editor in chief of the influential French bimonthly, the Jewish Tribune.

"The immense majority of French Jews do not agree with extremist groups," he added, "but they do not dare talk for fear of appearing to be giving arguments to Israel's adversaries."

With the start of the presidential elections set for April 21, French Jews find themselves increasingly isolated on the issue of Israel.

Indeed, only a few non-Jewish organizations were willing to officially back Sunday's protests.

Even the anti-racist group, SOS-Racism, which is headed by a Jew and which recently collaborated with the Union of French Jewish Students on a comprehensive study of anti-Semitism, abstained from participation in the main demonstration.

Moreover, only in Lyon did high-level politicians join the march.

According to one Paris protester, a student at the Sorbonne, "People who would normally be walking with us stayed away today because they did not want to be associated with anything that felt like a pro-Sharon rally."

Such sentiments were echoed in an editorial in Monday's edition of the popular French daily Liberation, which asked: "How can we protest the violence committed against the Jews of France without appearing to be a toy soldier following Sharon's steps?"