Belgian national Abdelhamid Abaaoud is the mastermind of the Paris terror attacks and is currently in Syria, sources close to the investigation told Reuters on Monday.
Meanwhile, there were conflicting report about the arrest of Saleh Abdeslam, the eight Islamic State terrorist who fled Paris after Friday's deadly attacks and has been the target of a massive manhunt. While Belgium's RTL reported Abdeslam, 26, was detained during a raid in the Brussels district of Molenbeek, the state-controlled RTBF carried a denial of the report.
The news comes as French police raided overnight homes of suspected Islamist militants across the country in the aftermath of the Paris shootings, and as French Prime Minister Manuel Valls warned of potential further attacks.
Valls said that since this summer, French intelligence services had prevented five attacks.
"We know that more attacks are being prepared, not just against France but also against other European countries," Valls said on RTL radio.
Also on Monday, French prosecutor Francois Molins said fingerprints from one of the suicide bombers behind the attacks at the Stade de France in Paris matched the prints of a man registered in Greece in October.
"At this stage, while the authenticity of a passport in the name of Ahmad al Mohammad, born Sept. 10 1990 in Idlib, Syria needs to be verified, there are similarities between the fingerprints of the suicide bomber and those taken during a control in Greece in October," the Paris prosecutor said in a statement.
The prosecutor also said a second bomber at the Bataclan concert hall had now been identified. The prosecutor named him as 28-year old Samy Ammour from Drancy, north of Paris and said he was known to counter-terrorism units after being placed under investigation and judicial control for attempting to go to Yemen.
He disappeared in the autumn of 2013 and an international arrest warrant was issued for him.
"Five of the terrorists killed have now been identified," prosecutor added.
Meanehile, Belgian police have carried out a new raid in the Brussels district of Molenbeek on Monday, state broadcaster RTBF said on its website.
"A large number of police launched a raid on a building in Rue Delaunoy," RTBF said.
The poor district of Molenbeek has been at the center of investigations of militant attacks in Paris over the weekend, after it emerged that two of the attackers had lived in the area.
110 house raids
Police sources told Reuters that authorities conducted at least 110 house searches in cities around France overnight. There were 23 arrests in the wake of the raids and 104 people are under house arrest, French Interior Minister Bernard Cazeneuve said.
One of these searches, in the Paris suburb of Bobigny, was part of the judicial investigation into the attacks at a football stadium, bars and a concert hall and where at least 129 people died.
The death toll was put 132 on Sunday, but reports on Monday said that increase may have been a counting error.
French media said police also raided houses in Toulouse, Grenoble and Bobigny.
"We are making use of the legal framework of the state of emergency to question people who are part of the radical jihadist movement...and all those who advocate hate of the republic," Valls said.
On Friday, three coordinated teams of gunmen and suicide bombers carried out the wave of attacks across Paris in what President Francois Hollande called an "act of war" by Islamic State.
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