
Prosecutors said one of the killers had been stopped and fingerprinted in Greece last month, fuelling speculation the Islamic State had taken advantage of the recent influx of refugees fleeing the Middle East to slip militants into Europe.
Paris shootings, explosions leave at least 128 dead
The Paris carnage, which killed 129 people, has led to calls for the European Union to close its borders to asylum seekers.
Prime Minister Manuel Valls warned France could be hit by new violence but said the Islamic State, which has claimed responsibility for the attacks in retaliation for French airstrikes in Iraq and Syria, would never win.
Interior Minister Bernard Cazeneuve told journalists on Monday police arrested 23 people and seized arms including rocket launchers in 168 raids overnight. Another 104 people were put under house arrest, he said.
"Let this be clear to everyone, this is just the beginning, these actions are going to continue," Cazeneuve said.
French warplanes pounded Islamic State positions in its Syrian stronghold Raqqa late Sunday - its biggest such strike since it started assaults as part of a US-led mission launched in 2014.
Islamic State video threatens France day after Paris bloodshed
The investigation into the coordinated Paris attacks, the worst atrocity in France since World War Two, led swiftly to Belgium after police discovered that two of the cars used by the militants had been rented in the Brussels region.
By Sunday, Belgian officials said they had arrested seven people in Brussels, while another man - one of three brothers believed to have been involved in the plot - was being hunted.
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