Millions of people were expected to join a march through Paris Sunday in solidarity with the victims of the Islamist attacks, with dozens of world leaders to attend the show of support for France.
French Prime Minister Manuel Valls predicted the massive turnout to honour the 17 killed in the attacks which targeted a satirical magazine, kosher supermarket and police.
"I have no doubt that millions of citizens will come to express their love of liberty, their love of fraternity," he told thousands gathered Saturday near where a gunman killed four hostages at the supermarket.
France has deployed thousands of police and troops to beef up security ahead of the march, which follows rallies across France on Saturday which drew more than 700,000 in support of the victims of the three-day killing spree.
"The real battle is to defend freedom of thought," said 40-year-old Yamina, tears in her eyes, at a rally in the southern city of Marseille.
A security force of around 2,200 will guard the route of Sunday's march, which will run three kilometres (1.9 miles) from the historic Place de la Republique to Place de la Nation in the east of the capital, the interior minister said, with snipers stationed on rooftops.
Dozens of world leaders including British Prime Minister David Cameron, German Chancellor Angela Merkel and Israeli Prime Minister Benjamin Netanyahu were set to attend Sunday's march.
Russian Foreign Minister Sergei Lavrov, Palestinian president Mahmud Abbas and the king and queen of Jordan are also among those set to take part.
Public transport will be free to ease access into and throughout Paris and international train operator Thalys said it was also cutting fares to the French capital on Sunday.
Far-right leader Marine Le Pen urged her supporters to attend rallies outside Paris, but not in the capital, denouncing the exclusion of her Front National party from preparations for the event.GUNMAN'S GIRLFRIEND STILL SOUGHT
The three gunmen responsible for the three-day reign of terror were shot dead by police on Friday, with investigators trying to track down the girlfriend of one of them.
Despite earlier being described as "armed and dangerous", security sources later revealed that 26-year-old Hayat Boumeddiene was not in fact in France at the time of the killings.
Her partner Amedy Coulibaly shot dead a young policewoman on Thursday and then killed four hostages in a siege at a Jewish supermarket in Paris on Friday.
While police initially suspected Boumeddiene may have had a role in her partner's violent acts, a Turkish security source told AFP she arrived in Turkey on January 2 and had since likely travelled on to Syria.
The three-day killing spree began Wednesday at the office of satirical magazine Charlie Hebdo that saw Cherif and Said Kouachi massacre 12 people including some of the country's best-known cartoonists. A day later, Coulibaly shot dead the policewoman.
The massive manhunt for the two brothers developed into a car chase Friday and then a tense standoff as they took one person hostage in a printing firm northeast of Paris.
The small town of Dammartin-en-Goele was transformed into what looked like a war zone, with elite forces deploying snipers, helicopters and heavy-duty military equipment as they surrounded the pair.
With all eyes on the siege outside Paris, suddenly explosions and gunfire shook the City of Light itself as Coulibaly stormed a Jewish supermarket on the eastern fringes of the capital.'APPALLING ANTI-SEMITIC ACT'
In what President Francois Hollande called an "appalling anti-Semitic act", Coulibaly took terrified shoppers hostage hours before the Jewish Sabbath, killing four.
As the sun set, the brothers in Dammartin-en-Goele charged out of the building with guns blazing in a desperate last stand, before being cut down.
Within minutes, elite commando units moved in Paris against Coulibaly, who had threatened to execute his hostages unless the brothers were released.
Up to five people -- including a three-year-old boy -- survived hidden inside a refrigerator for five hours, with police pinpointing their location using their mobile phones, prosecutors and relatives said.
In the printing firm, the brothers took the manager hostage, later releasing him after he helped Said with a neck wound, while a second man hid beneath a sink upstairs.
After Friday's dramatic events, Hollande warned grimly that the threats facing France were not over -- comments followed by a chilling new threat from the Yemen-based Al-Qaeda in the Arabian Peninsula group.
AQAP top sharia official Harith al-Nadhari warned France to "stop your aggression against the Muslims" or face further attacks, in comments released by the SITE monitoring group.
German newspaper Bild said the bloodshed in France could signal the start of a wave of attacks in Europe, citing communications by Islamic State leaders intercepted by US intelligence.
It said the US National Security Agency had intercepted communications in which leaders of the jihadist group announced the next wave of attacks, the tabloid said in its Sunday edition, citing unnamed sources in the US intelligence services.'CLEAR FAILINGS'
Questions are mounting over how the three gunmen slipped through the security net, and Valls admitted there had been "clear failings" in intelligence.
Cherif Kouachi, 32, was a known jihadist who was convicted in 2008 for involvement in a network sending fighters to Iraq.
His brother Said, 34, was known to have travelled to Yemen in 2011, where he received weapons training from AQAP.
It also emerged that the brothers had been on a US terror watch list "for years".
Coulibaly, 32 -- who met Cherif Kouachi in prison -- was sentenced to five years in prison in 2013 for his role in a failed bid to break an Algerian Islamist, Smain Ait Ali Belkacem, out of jail.
Coulibaly's mother and sisters on Saturday condemned his actions.
"We absolutely do not share these extreme ideas. We hope there will not be any confusion between these odious acts and the Muslim religion," they wrote in a statement.