Prosecutor Francois Molins told a news conference the Forsane Alizza group, or Knights of Pride, did physical training in parks and forests, collected weapons and preached hate and violence on their Internet site, showing clips of late al-Qaida leader Osama bin Laden.
The site was shut down after authorities banned Forsane Alizza in March.
The 13 — among 17 suspects detained in police raids last week — faced preliminary charges of criminal association linked to a terrorist network, a sweeping charge with a maximum 10-year prison term that is used in France to ensure a full investigation of terror suspects.
Nine of the 13 are being jailed, Molins said. Charges of acquiring, transporting and detention of arms also were issued.
The remaining four who had been detained were being released.
The prosecutor said several terror plans appeared to be in the works, including the kidnapping of a judge in Lyon, in southeast France. An official close to the investigation said the targeted judge is Jewish.
"All the suspects confirmed Mohammed Achamlane's role of animator, coordinator and emir and his constant concern about acquiring weapons," Molins said.
Molins said the alleged plan to kidnap a magistrate who dealt with a child abuse case of a member of the Lyon cell was hatched at a September meeting. The magistrate in question has been placed under police protection.
Other potential targets included people from groups that have spoken out against the Muslim community, the prosecutor said without elaboration.
It was not known whether this was a reference to groups actively seeking to protect the French identity and decrying what they claim is the Islamization of France.
Such groups are gaining strength around France, and have been joined by far-right presidential candidate Marine Le Pen.
Police found stashes of weapons during their raids last Friday in the Paris region and the cities of Nantes, Marseille, Nice, and Toulouse as well as documents and computer equipment.
The probe so far has shown that members had consulted Internet sites showing how to make explosives, Molins said.
The prosecutor stressed the group had no link to the three attacks last month around Toulouse that left seven people dead — three paratroopers, a rabbi and three Jewish school children.
Gunman Mohamed Merah, 23, who had claimed links to al-Qaida, was killed after a long armed standoff with police.
Authorities have said his case was an example of so-called lone wolf terrorism, contending he radicalized alone in his prison cell.
However, investigators are still searching for any potential accomplices of Merah's and his older brother remains in custody.