Cherif Kouachi, one of two brothers who killed 12 people in the attack on the satirical weekly March 7th, was buried just before midnight Saturday in a cemetery in Gennevilliers, a day after his older brother Said was discreetly buried in the northeastern city of Reims.
Cherif's family, including his widow, kept away from the funeral, the mayor's office said, and the grave was left anonymous to avoid it becoming "a pilgrimage site" for Islamists.
The brothers were shot dead by police after a three-day manhunt following the slaughter at Charlie Hebdo, which had angered many Muslims around the world with its repeated publication of cartoons lampooning Islam's Prophet Muhammad.
Anger erupted in a string of majority Muslim countries after the satirical magazine responded to the massacre by running another caricature last week, showing the prophet under the headline "All is forgiven".
The worst unrest has been in Niger, where at least five people were killed and some eight churches were torched Saturday. Around 1,000 youths wielding iron bars, clubs and axes rampaged through the capital, hurling rocks at police who responded with tear gas.
Demonstrators attending a banned political rally unconnected to the Charlie Hebdo controversy clashed with police in the capital Niamey on Sunday.
Meanwhile, a memorial rally was due in Paris on Sunday in memory of policewoman Clarissa Jean-Philippe, who was gunned down by Amedy Coulibaly, another Islamist gunman who claimed to be working with the Kouachi brothers and was also shot by police.
French investigators were focusing on 12 people detained early Friday and being questioned over "possible logistical support" they may have given to the Paris gunmen, sources said.
Neighbouring Belgium deployed troops on the streets for the first time in 35 years after security forces this week smashed a suspected Islamist "terrorist" cell planning to kill police officers.
Greek anti-terror police arrested at least four people suspected of links to the dismantled jihadist cell on Saturday.
However, authorities said Sunday that there was no link between those detained and the Belgium cell.
A Greek police source said investigators had sent DNA evidence and fingerprints to Belgium to establish whether Abdelhamid Abaaoud, the 27-year-old suspected mastermind of the Belgian cell, was among the four.
"There is no connection between these people and the enquiry" in Belgium, Eric Van Der Sypt, spokesman for the federal prosecutor's office, said.
The violence in France and Belgium and the continuing security crackdown has highlighted fears in Europe over the threat posed by residents returning home after fighting alongside Islamist groups in Syria.
Britain will hold a meeting of the coalition against the Islamic State group on Thursday, two weeks after the Paris attacks by gunmen claiming to act on behalf of the jihadist group and Al-Qaeda.
Foreign Secretary Philip Hammond and US Secretary of State John Kerry will host the one-day talks in London to discuss progress on tackling the Islamist militants.
French Foreign Minister Laurent Fabius condemned "the use of violence" in Niger while President Francois Hollande said France was committed to "freedom of expression", calling it "non-negotiable".
In a speech, Hollande urged his compatriots not to change their habits, because "to do so would be to yield to terrorism".
A survey released Sunday however found 42 percent of French people thought publications should avoid running cartoons of Mohammed, and 50 percent favoured limiting freedom of expression on the Internet and on social networks, according to the poll for the weekly Le Journal du Dimanche.
Charlie Hebdo's chief editor has defended the cartoons, saying they safeguard freedom of religion.
"Every time we draw a cartoon of Muhammad, every time we draw a cartoon of prophets, every time we draw a cartoon of God, we defend the freedom of religion," Gerard Biard told NBC's "Meet the Press" programme.
The mayor of Gennevilliers, where the younger Kouachi brother Cherif lived and was buried, had not wanted the funeral to go ahead, but said he had no legal means to block it.
He did, however, prevent the burial of Said Kouachi, who had not lived in the area. Said was instead buried in Reims on Friday, under heavy police protection with a handful of family members present, according to a source familiar with the event.
Charlie Hebdo says it has sold 2.7 million copies of the post-killings issue in France alone and that it would extend its print run to seven million copies.
Before the assault on its Paris headquarters, Charlie Hebdo had a circulation of around 30,000, with only a handful being sold abroad.
To limit the overwhelming burden on our moderators, it will not be possible to comment on this article. Feel free to join the conversation on our Facebook page.