Three French nationals, a Franco-Algerian and a Malian were arrested Tuesday in the Paris region as part of a probe into a network to send jihadists to fight in west Africa, police said.
Police provided no further information about the arrests but Interior Minister Manuel Valls said they were linked to the capture of an individual on the Mali-Niger border several months ago.
Earlier, police reported that three French-Congolese and one Malian had been arrested.
According to a judicial source, all four are aged between 23 and 37 and have links to Cedric Lobo, a Frenchman who was arrested in Niger last year on his way to Timbuktu to join Islamist groups in northern Mali.
The four were linked to a mosque in the Paris suburb of L'Hay-les-Roses that Lobo used to live in.
The probe is being conducted by French intelligence agents, a police source said.
According to Valls, there are people who want to go to west Africa, where the French army last month deployed to fight Islamist militants occupying the north of Mali.
A "handful" of French would-be jihadists are probably already in Mali, the defence minister said.
As well as Lobo, police had arrested another person in Mali, Valls said.
"We have to continue dismantling these networks that either want to act on our territory or take individuals for jihad" abroad, he said.
He said that several dozen French nationals had also travelled to Syria to fight in the conflict there, sometimes in groups linked to Al-Qaeda.
French forces intervened in Mali last month to halt an advance on the capital Bamako by Islamists who seized a swathe of the north last year.
With the Malian army, the French have taken back large chunks of territory from the militant groups, but concerns remain that the fighters have simply gone underground.