PARIS (AP) — French authorities have filed preliminary charges against five people, including a sister and brother, suspected of belonging to a ring specialized in recruiting young female fighters for the Islamic State group in Iraq and Syria.

A judicial official said Sunday the five were arrested Tuesday and Wednesday in Vaux-en-Velin in central France and were being held in custody.

The arrests came weeks after a series of detentions of adolescent girls around France, including a 16-year-old caught at the airport in Nice as she prepared to leave for Turkey and ultimately Syria, and three teens who were planning to travel abroad together and corresponded on social networks.

France is trying to make it harder both to recruit would-be jihadis, including a plan to let the government seize their passports.

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