Four men aged between 22 and 35 have been arrested in the Paris region for allegedly belonging to a militant network sending fighters to Syria, informed sources said Friday.

Four men aged between 22 and 35 have been arrested in the Paris region for allegedly belonging to a militant network sending fighters to Syria, informed sources said Friday.

The arrests by investigators from France's intelligence agency DCRI took place on Tuesday and the presumed leader of the network is a 24-year-old man, according to sources close to the case.

At least two of the other men went to Syria to fight for the Al-Nusra Front. A woman was also arrested but released later.

Three of the men were born in France and one in Morocco.

An informed source said about 440 people from France were either currently fighting in Syria's civil war, planning to go and fight or had recently returned.

Half this number were there at present, about 10 had been killed and between 50 and 60 had returned, the source said.