French Interior Minister Bernard Cazeneuve on Wednesday announced a free phone number - 0 800 005 696 - to alert the authorities about would-be jihadi fighters, as part of a campign to clamp down on jihadi networks.
The announcement comes just days after the release of four French journalists who had been held hostage in Syria.
They said several of their captors spoke French.
"It is a European concern," said Cazeneuve during a meeting with his European counterparts in London, which had decided to "go further in dismantling these networks".
Cazeneuve praised a British initiative of distributing testimony of disillusioned youngsters who have returned from fighting.
"It will inspire all of us," he added.
A planned meeting in Brussels whould lead to tighter cooperation between EU countries and with Morocco, Jordan, Tunisia and Turkey.
According to the interior ministry, about 285 French people are currently fighting in Syria, so a 75 per cent rise in the past six months.
Another 120 are believed to be on the way to Syria, 25 to have been killed and 100 to have returned to France after having taken part in fighting.
Among them 116 women and 30 minors have been enrolled in the networks.