The suspects were apprehended in England with more than 100 kilogrammes of pure gold worth some €2 million. Authorities also found £150,000 (€190,000) in cash on the smugglers.
Customs officials believe the group took at least 80 trips through Frankfurt from Dubai on the way to London.
British authorities estimate the smugglers were avoided €6.4 million in taxes between 2004 and 2008.