The 15-day trial underscored the concerns of French and other European officials over Europeans returning from war zones in Syria which has attracted more would-be jihadis than Afghanistan.
The court handed down sentences ranging from two to nine years in prison. Three of the defendants were tried in absentia, including Touhami Tebourski, who is in custody in Turkey awaiting extradition to France, and was sentenced to nine years. Two others are at large.
Tebourski is one of four defendants that the prosecution said spent time in the Pakistan-Afghanistan border zone, a haven for al-Qaida and Taliban militia fighters.
The court ruled the group had "varying commitments" to a "perfectly organized" network but said there was no "clearly defined" project for attack.
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The prosecutor had sought the maximum 10-year sentence. Both the prosecution and the defendants can appeal the verdict.
"For the time being, we are satisfied with the decision," said Julia Mas, a lawyer for Ryad Hennouni, a 27-year-old arrested in Naples, Italy, in 2010. "We were expecting a worse sentence."