The Belga news agency, citing the prosecutors office, gave no details of the charges they could face.
The authorities have released another 16 people picked up in connection with the dramatic February robbery after questioning, the agency added.
More than 30 people were initially detained by police in Belgium, France and Switzerland in raids which recovered a large quantity of diamonds and cash, officials said yesterday.
The February 18 robbery at Brussels' Zaventem airport was described as "one of the biggest" ever by the Antwerp World Diamond Centre (AWDC), the global dealers' syndicate based in the Belgian port city.
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In an operation that lasted barely 10 minutes and without a shot fired, the men forced open the hold of the plane and removed some 120 boxes of diamonds.
The gang, posing as police officers, had cut through the airport's perimeter fence and made off with the haul of USD 50 million dollars in gems.
A Swiss statement yesterday said a businessman and a Geneva lawyer were among eight people being held there.