Abdelhamid Abaaoud, a Belgian of Moroccan origin suspected of masterminding the attacks that left 129 people dead in the name of the Islamic State group, died in Wednesday's assault by police on an apartment in northern Paris.
The 28-year-old was thought to have been in Syria, where he had boasted of planning attacks on the West, and his presence in France has raised questions about Europe's handling of the region's worst migrant crisis since World World II.
French Interior Minister Bernard Cazeneuve said Paris had received no warning from other EU members that Abaaoud was in the bloc, and it was "urgent that Europe wakes up, organises itself and defends itself against the terrorist threat".
European Union interior and justice ministers are to meet in Brussels where they will discuss tightening checks on all travellers at the external borders of the 26-nation Schengen zone as an emergency measure.
French Prime Minister Manuel Valls said some of the killers in the Paris attacks had taken advantage of Europe's migrant crisis to "slip in" unnoticed and warned the cherished Schengen zone would be in danger if the bloc did not improve border controls.
Abaaoud's links to Syria and the discovery of a Syrian passport near the dead body of one of the gunmen have also stoked concerns elsewhere that terrorists could be posing as refugees from the war-torn country as a cover for plotting attacks.
In the US, the Republican-dominated Congress on Thursday voted to ban Syrian and Iraqi refugees from entering the United States until tougher screening measures are in place.
And in Russia, itself still reeling after a Russian passenger plane was downed in Egypt killing 224 people on board in another attack claimed by ISIS, both chambers of parliament will hold extraordinary meeting on tacking terrorism today.
Abaaoud was the subject of an international arrest warrant issued by Belgium, where a court had in July sentenced him in absentia to 20 years in prison for recruiting terrorists for Syria.
But it was only three days after the Paris bloodbath that "intelligence services of a country outside Europe indicated they had knowledge of his presence in Greece", Cazeneuve said, without specifying which country.
Abaaoud was also checked by police at Cologne-Bonn airport on his way to Istanbul in early 2014, German officials said, but was allowed to go as they had no indication he should be stopped.
He was finally tracked down in Paris after a tip-off from Moroccan intelligence services, according to police sources.
At least 129 people were killed and hundreds wounded in the shootings and suicide bombings that targeted a concert hall, bars and restaurants and the Stade de France national stadium a week ago.
It was the second major attack in Paris in less than a year. In January, terrorist gunmen killed 17 people at Charlie Hebdo satirical magazine, on the streets and in a Jewish supermarket.
Abaaoud was involved in four out of six attack plots foiled in France this year, Cazeneuve said. Police are also probing links to a thwarted assault on a high-speed train from Amsterdam to Paris in August.
As the probe widened across Europe, Belgian police arrested nine people in Brussels, seven in raids linked to a suicide bomber who took part in the Paris attacks.
Italy was also hunting five suspects after an FBI tip-off about possible terrorist attacks on landmark sites.
'In her own bubble'
Paris prosecutor Francois Molins said fingerprint analysis was used to identify Abaaoud's body, found riddled with bullets in the rubble of the shattered building in Saint-Denis following a seven-hour police siege.
A body thought to be Abaaoud's 26-year-old cousin Hasna Ait Boulahcen, who detonated an explosives vest, was also found at the scene.
Speaking to AFP before police raided a house northeast of Paris where Boulahcen had lived with her mother and siblings, her brother said she had become radicalised only around six months ago.
"She was unstable, she created her own bubble. She wasn't looking to study religion, I have never even seen her open a Koran," he told AFP.
Eight arrests were made in Wednesday's massive raid in Saint Denis, but another key suspect, Salah Abdeslam, remains unaccounted for.
Abdeslam is thought to be one of the only surviving members of the group of assailants behind the Paris attacks. His suicide-bomber brother Brahim Abdeslam blew himself up at a cafe without killing anyone.
French lawmakers on Thursday voted to extend an extraordinary package of security measures for three months as Valls warned of "the risk from chemical or biological weapons".
The measures include allowing police to carry weapons when they are off duty and use them in the event of an attack. French MPs also voted to let the government block websites and social media accounts promoting or inciting terrorist acts.
Get Breaking news, live coverage, and Latest News from India and around the world on NDTV.com. Catch all the Live TV action on NDTV 24x7 and NDTV India. Like us on Facebook or follow us on Twitter and Instagram for latest news and live news updates.