Members of the Islamist group Forsane Alizza plotted to kidnap a Jewish judge in the central city of Lyon, according to French media reports.
Nineteen suspected radicals were arrested in raids across France last week, 13 of whom will face charges related to terrorism, prosecutors said today.
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Sources close to the investigation told Europe 1 radio that the group had identified a magistrate in Lyon, Albert Lévy, as a potential kidnapping target.
Prosecutors have confirmed that the judge ruled on previous charges against one of the men detained, who was sentenced to two years in prison in June 2010 for neglecting his five children and stopping them attending school.
Paris prosecutor François Molins told a press conference this morning that people who had made anti-Muslim statements in public or online were also named as targets.
Forsane Alizza members discussed the plot in September 2011 and it remained in the "hypothetical" stage, Molins said. Lévy has nonetheless been placed under police protection.
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Authorities decided to arrest the suspects when information indicated that they were preparing to take "imminent action," according to the prosecutor. He said magistrates did not want to "take risks."
The head of France's domestic intelligence agency, the DRCI, has said that the suspects received physical training and religious indoctrination. "There were collective war-like training sessions," Bernard Squarcini told regional newspaper La Provence.
The 13 men now under formal investigation will face charges of being part of a criminal gang connected to a terrorist enterprise, Agence France Presse said.
A lawyer for the man considered the leader of Forsane Alizza, Mohamed Achamlane, said his client denied "any terrorist intention" or link to the Toulouse shooter and self-proclaimed mujahedeen, Mohamed Merah.
Achamlane believes the crackdown on suspected Islamist radicals is an attempt to win favor with voters ahead of France's presidential election, attorney Benoit Poquet told local newspaper Presse-Océan.
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