PARIS (AP) — Hackers have targeted about 19,000 French websites since a rampage by Islamic extremists left 20 dead last week, a top French cyberdefense official said Thursday as the president tried to calm the nation's inflamed religious tensions.

France is on edge since last week's attacks, which began Jan. 7 at the satirical newspaper Charlie Hebdo. The paper, repeatedly threatened for its caricatures of the Muslim Prophet Muhammad, buried several of its slain staff members Thursday even as it reprinted another weekly issue with Muhammad on its cover.

Calling it an unprecedented surge, Adm. Arnaud Coustilliere, head of cyberdefense for the French military, said about 19,000 French websites had faced cyberattacks in recent days, some carried out by well-known Islamic hacker groups.

The attacks, mostly relatively minor denial-of-service attacks, hit sites as varied as military regiments to pizza shops but none appeared to have caused serious damage, he said. Military authorities launched round-the-clock surveillance to protect the government sites still coming under attack.

"What's new, what's important, is that this is 19,000 sites — that's never been seen before," Coustilliere said. "This is the first time that a country has been faced with such a large wave."

Among the groups suspected of launching the attacks, French officials named MECA: Middle East Cyber Army, Fallaga team and Cyber Caliphate.

According to Arbor Networks, a private company that monitors Internet threats, in the past 24 hours alone, France was the target of 1,070 denial of service attacks. That's about a quarter as many as the United States, but the U.S. hosts 30 times as many websites.

Coustilliere called the attacks a response to the massive demonstrations against terrorism that drew 3.7 million people into the streets Sunday across France. He pointed to "structured groups" that used tactics like posting symbols of jihadist groups on companies' Web sites.

Two of the Paris terror attackers claimed allegiances to al-Qaida in Yemen and a third to the Islamic State group.

Meanwhile, Belgian authorities were looking into possible links between a man they arrested in the southern Charleroi region for illegal trade in weapons and the Paris kosher grocery attacker, Amedy Coulibaly.

"The man claims that he wanted to buy a car from the wife of Coulibaly," said federal prosecutor's spokesman Eric Van der Sypt. "At this moment this is the only link between what happened in Paris."

The terror attacks in Paris occurred in an atmosphere of rising anti-Semitism in France and have prompted scattered retaliatory violence against Muslims and Muslim sites around France. Justice officials have also been cracking down by arresting dozens of people who glorified terrorism or made racist or anti-Semitic remarks.

French President Francois Hollande insisted Thursday that any anti-Muslim or anti-Semitic acts must be "severely punished." He said France's millions of Muslims should be protected and respected, "just as they themselves should respect the nation" and its strictly secular values.

"In the face of terrorism, we are all united," he said at the Institute of the Arab World in Paris.

The government announced Thursday it would give citizenship to a Malian immigrant who saved several Jewish shoppers last week by hiding them in the kosher market's basement before sneaking out to brief police on Coulibaly, the hostage-taker upstairs. Interior Minister Bernard Cazeneuve said he would personally preside over the ceremony for Lassana Bathily on Tuesday.

Among the victims buried Thursday were Charlie Hebdo cartoonists Georges Wolinski and Bernard Verlhac, both laid to rest in Paris' famed Pere-Lachaise cemetery. Verlhac, who drew under the name Tignous, was buried in a plain wood coffin decorated with cartoons by his friends.

Three other victims of the attacks — Charlie Hebdo columnists Bernard Maris and Elsa Cayat, and Franck Brinsolaro, the policeman bodyguard for slain Charlie Hebdo chief Stephane Charbonnier — were also buried Thursday.

With 120,000 security forces deployed to prevent future attacks, nerves jumped overnight when a car rammed into a policewoman guarding the president's palace. Prosecutors and police said, however, the incident at the Elysee Palace had no apparent links to last week's shootings.

A car carrying four people took a one-way street in the wrong direction then drove off when the police officer tried to stop them. The officer sustained slight leg injuries, police said. Two people were later arrested and two others in the car fled.

Customers lined up again Thursday to try to get copies of Charlie Hebdo's first edition since the attacks. Even though it had a special increased print run of 5 million copies, it sold out before dawn Thursday in Paris kiosks for a second straight day.

Some Muslims, who believe their faith forbids depictions of the prophet, reacted with dismay or anger to the new cover. In Pakistan, lawmakers marched outside parliament Thursday to protest the publication.

A leader of Yemen's al-Qaida branch officially claimed responsibility for the attacks at Charlie Hebdo, saying in a video the slayings were in "vengeance for the prophet." But U.S. and French intelligence officials lean toward an assessment that the Paris terror attacks were inspired by al-Qaida but not directly supervised by the group.

Speaking on the papal plane, Pope Francis expressed his belief that there were limits to freedom of expression, using Alberto Gasparri, who organizes papal trips and was standing by his side, as an example.

"If my good friend Dr. Gasparri says a curse word against my mother, he can expect a punch," Francis said, throwing a pretend punch. "You cannot provoke. You cannot insult the faith of others. You cannot make fun of the faith of others."

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Angela Charlton, Lori Hinnant, and Nicolas Vaux-Montagny in Paris, Nicole Winfield on the papal plane, Raf Casert in Brussels and Matthew Lee in Sofia, Bulgaria contributed to this report.