The ring is thought to have bought children from Macedonia or Kosovo for €1000 to €1500 and then sold them on to Belgium and Germany for €10,000.
Seven members of a family originally from the Balkans were arrested on Tuesday after a month of police investigation.
According to local paper Est Républicain, several other members of the family had also been arrested in Germany in relation to the ring.
Police took in two girls, both about 12-years-old, for questioning. They say they do not believe the girls were subjected to sexual abuse or used as slaves, but traded in line with "local customs" in the traffickers' home countries.
“The objective of the people in charge of this inquiry is to determine what these two children have suffered and how many other victims there are,” said one officer close to the case.
“Clearly this is not a torturous or barbaric trafficking ring... We don’t where the girls were going to be sold onto.”
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