For many in Israel, the deadly attack on a kosher supermarket in Paris was further evidence that France is becoming hostile territory for Jews and authorities are unable to protect them.

"I'm angry with French Jews. Why are they hesitating to pack their bags and come here? France has become a dangerous place for the Jews," said Manuel Allal, a 26-year-old French-Israeli sitting in an Internet cafe in Jerusalem. 

At least two of the gunmen who unleashed terror on France are believed to have been radicalized in prison, a fertile ground for extremism that authorities are struggling to contain.

Both Mohamed Merah, the al-Qaida militant who shot dead seven people in a series of 2012 attacks, and Mehdi Nemmouche, last year's Brussels Jewish museum killer, were radicalized in jail.

Morocco's Foreign Minister Salaheddine Mezouar snubbed the mammoth march against extremism through Paris on Sunday due to the presence of "blasphemous cartoons depicting the Prophet," the ministry said.

He nevertheless went to the Elysee Palace to present the country's "sincere condolences to the French president and to the French government following the despicable attacks in France this week."

France's far-right National Front (FN) held a demonstration of its own against terrorism on Sunday, after being excluded from a massive unity rally in Paris.

Party leader Marine Le Pen led a demonstration in the FN-controlled southern town of Beaucaire after denouncing what she called the "exclusion" of her party from Paris march, which drew more than a million people in solidarity with the 17 victims of terror attacks  this week.

Four French Jews killed during an Islamist attack on a kosher supermarket in Paris are to be buried in Israel on Tuesday, community sources and the Israeli premier said.

"The four families decided to bury their dead in Israel. The funerals will be held on Tuesday at 10 am (0800 GMT) at the Mount of Olives cemetery" in Jerusalem, a Jewish community source told Agence France-Presse in Paris.

The wife of Charlie Hebdo attacker Cherif Kouachi, held for 72 hours after the deadly assault, has condemned her husband's actions and expressed her feelings for the victims, her lawyer told Agence France-Presse on Sunday.

Speaking after she was released from custody on Saturday, Christian Saint-Palais said the young woman had "expressed her indignation and condemnation of violence" to investigators.

U.S. Attorney General Eric Holder said Sunday there was no "credible information" as yet that al-Qaida was behind the attacks in France that killed 17 people.

Holder spoke as dozens of heads of states joined hundreds of thousands of people in a massive display of unity and defiance against terrorism on the streets of Paris.

Tens of thousands of people rallied worldwide in solidarity with France on Sunday, with marchers across Europe and the Middle East chanting "Je suis Charlie" and holding pens in the air.

From Berlin to London and Jerusalem to Beirut, crowds waved French flags and sang the anthem La Marseillaise following the Islamist attacks that killed 17 people.

Francois Hollande, Angela Merkel and Petro Poroshenko met briefly at the French presidency in Paris Sunday to discuss the Ukrainian crisis before leaving to take part in a historic march against terrorism.

Russia's Foreign Minister Sergei Lavrov, who was also present to attend the demonstration, did not go to the talks, the presidency said.

From the vicious rape of a woman because her partner is Jewish to this week's deadly shooting at a kosher supermarket, a soaring number of anti-Semitic attacks is making many Jews wonder if they should simply leave France.

"If I were 30, I would get out of France" and move to Israel, said Laurent S., who would not give his family name.