Two people have been arrested and another two are being sought on suspicion of selling fuel that was destined for Albania in Greece, thus depriving the state of an unspecified amount of much-needed taxes.
A 59-year-old Albanian fuel truck driver and 42-year-old Greek man were arrested in northern Greece.
The owner and manager of a fuel trading company based in Albania are wanted by police.
The gang allegedly exported smaller quantities of duty-free fuel to Albania than it reported to authorities and sold the remainder in Greece.
It used fuel trucks that were specially designed to fool customs officials.