The total includes 350 on the ground in Iraq and Syria says interior minister on eve of Iraq security conference in Paris.
The 16-year-old girl was detained in Nice along with a 20-year-old man suspected of being her recruiter to join jihadist forces in Syria.
The 16-year-old, who is now in police custody in France, headed to Syria to fight after telling his father he was going to a nightclub.
The four were detained in Marseille over allegations that they have been helping to recruit volunteers for radical Islamist networks in Syria.
French interior minister says Souad Merah, whose brother shot dead seven people in south-west France in 2012, is believed to be in Syria.
A raft of new measures aimed at preventing the growing number of French nationals joining jihadist movements in Syria was approved at a meeting of the French cabinet on Wednesday. Official estimates are that 700 French citizens and residents have joined jihadist groups engaged in the three-year old civil war against the regime of President Bashar al-Assad, some of them teenagers. The issue was highlighted during the release last weekend of four French journalists who had been kidnapped in Syria by an al-Qaeda-linked group, when they said they had identified francophones among their captors. To understand more about just who the French jihadists are, and what motivates them, Mediapart Arab affairs correspondent Pierre Puchot turned to Radio France International journalist David Thomson, who carried out in-depth interviews with 18 of them for his recently-published book Les Français jihadistes.
Expert says the Islamic State in Iraq and the Levant (ISIL) jihadist group in Syria lacks funding 'so they have to use their hostages'.
Hamza Madhouj says he took daughter, aged two, to Syria to obey obligation for all Muslims not to live in a non-Muslim country and that she is safe.
The pair were brought back to France having gone to Turkey in early January with the intention of joining Islamist fighters in Syria.
The father of one of two 15 year-olds who ran away from their homes in Toulouse to join jihadists in Syria said he was 'brainwashed online'.
Mother had sent her three-year-old son to school in a T-shirt reading 'I am a bomb' and 'Jihad, born on September 11'.
The groups had already jointly claimed responsibility for raids that killed dozens at a barracks and damaged a uranium mine operated by French firm.
Court in Avignon clears mother who sent her 3-year-old son to school in a tee-shirt reading "I am a bomb" and "Jihad, Born on September 11".
Anti-terror judge tells media he is worried about the implication of large numbers of French Muslims heading to Syria to fight a holy war.