An Interior Ministry statement today says the unidentified Tunisian was sent back to Tunisia on Thursday "in view of the threat his presence constituted for public security and the safety of the state."
The ministry says the man had "played a central role" in the jihadi recruitment ring in the Grenoble area.
France believes it has more of its young people joining the Syria fighting than any other European nation.
In April the government announced a series of measures aimed at dismantling recruiting networks, including an alert system for parents who fear their children are at risk of taking up jihad.