The raid in June seized over 2,400 shipping containers at the port of Piraeus, primarily filled with e-bikes, textiles and footwear.

The haul was worth at least 250 million euros ($294 million), the agency said in a statement.

Two customs officers have been charged with repeated false certification, causing unlawful gains and damage of over 871,000 euros, and with abetting customs fraud.

The other four are customs brokers who have been charged with repeated customs fraud and false certification.

"It is suspected that the customs brokers under investigation declared the same amount of containers for importation on a monthly basis, for years," the agency said.

It noted that the scam had been ongoing for at least eight years, causing an estimated loss of at least 350 million euros in customs duties and 450 million euros in VAT sales tax.