PARIS (AFP) - France deployed hundreds of troops around Paris Saturday, beefing up security on the eve of a march expected to draw more than a million in tribute to 17 victims of a three-day Islamist killing spree.
Fears remained acute and security levels were kept at France's highest level as the girlfriend of one of three gunmen killed in a fiery climax to twin hostage dramas on Friday remained on the loose.
But refusing to be cowed, people poured onto the streets in cities around France in poignantly silent marches paying tribute to those killed in the nation's bloodiest week in more than half a century.
The marches in the cities of Nice, Pau and Orleans were a taste of what was to come in Paris Sunday, where a monster rally will be held for national unity, to be attended by President Francois Hollande and a host of world leaders.
The defence ministry said it was sending another 500 soldiers into the greater Paris area, bringing current numbers to what will be some 1,350 troops.
After Friday's dramatic events, Hollande warned grimly that the threats facing France "weren't over", comments followed by a chilling new threat from a Yemen-based Al-Qaeda group.
Security forces were focused on hunting down 26-year-old Hayat Boumeddiene, the "armed and dangerous" partner of Amedy Coulibaly who took terrified shoppers hostage in a Jewish supermarket on Friday, killing four of them.
Before he was killed by elite police in a massive assault on the store, he told journalists he was a member of the Islamic State in Iraq and Syria (ISIS) extremist group.
Coulibaly and Boumeddiene are the prime suspects in the murder of a policewoman on Thursday just outside the French capital. That attack further spooked a nation still reeling from the Wednesday assault at the Charlie Hebdo satirical weekly in Paris that saw two gunmen mow down 12 people including some of the country's best-known cartoonists.
In a sombre address after Friday's sieges, Hollande said: "I call on all the French people to rise up this Sunday, together, to defend the values of democracy, freedom and pluralism to which we are attached."
But as leaders urged the country to pull together in grief and determination, questions were also mounting over how the three men - brothers Cherif and Said Kouachi, and Coulibaly - had slipped through the security net after it emerged that all three were known to the intelligence agencies.
- 'Appalling anti-Semitic act' -
France's darkest week in decades came to an explosive end on Friday after the gunmen holed up in two hostage dramas some 30 kilometres apart.
The massive manhunt for the two Kouachi brothers developed into a car chase and then a tense standoff as they held a 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. In what Hollande called an "appalling anti-Semitic act", Coulibaly took terrified shoppers hostage hours before the Jewish Sabbath, killing four.
As the sun set on the horrified capital, the brothers charged out of the building with guns blazing in a desperate last stand, before being cut down.
Within minutes, elite commando units moved against Coulibaly, who had threatened to execute his hostages unless the brothers were released. Coulibaly had just knelt for his evening prayer when the special forces struck. Explosions rocked the neighbourhood - one lighting up the shopfront in a fireball - and shooting erupted as the commandos burst in.
"It's war!" shouted a mother as she pulled her daughter away. 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.
- 'Clear failings' -
As the drama reached its climax, links emerged showing the brothers and Coulibaly were close allies and had worked together. All three had a radical past and were known to French intelligence.
Cherif Kouachi, 32, was a known extremist 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 Al-Qaeda in the Arabian Peninsula (AQAP).
It also emerged that the brothers had been on a US terror watch list "for years".
Cherif told French TV he was acting on behalf of the Yemen-based AQAP while Coulibaly said he was a member of ISIS.
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. Boumeddiene and Cherif's girlfriend spoke "more than 500" times by phone in 2014, said Paris's chief prosecutor Francois Molins.
Prime Minister Manuel Valls said the carnage they left in their wake showed there had been "clear failings" in intelligence.
The Islamic State group's radio praised them as "heroes" and Somalia's Shebab militants, Al-Qaeda's main affiliate in Africa, hailed their "heroic" act.
Meanwhile AQAP top sharia official Harith al-Nadhari chillingly warned France to "stop your aggression against the Muslims" or face further attacks, in comments released by the SITE monitoring group.