The arrest of 57-year-old Ngo Van Thuy, an officer of the anti-smuggling and investigation department under the General Department of Vietnam Customs, was part of an ongoing investigation into a ring producing and trading counterfeit fuel in Mekong Delta's Vinh Long Province, busted by police last month.

Officers had raided Thuy's residence and workplace in Ho Chi Minh City and seized many documents related to the case, police said Saturday.

The large-scale raid occurred after police in Dong Nai received reports from locals on low quality gasoline being sold by several stations in the province. Dong Nai police detected a fake gasoline production ring and collaborated with colleagues in other southern provinces and the Ministry of Public Security to bust it.

A large team of 500 police raided an islet in the middle of Hau River last month and found people producing fake fuel there. The gangsters resisted fiercely, crashing a large boat into the police vessel as they tried to escape from the islet in Vinh Long's Binh Minh District. However, police prevailed.

Simultaneously, other police officers raided a series of gasoline stations in Long An, Can Tho, Dong Nai, Vung Tau and HCMC.

Police have so far arrested 35 people involved in the ring, led by Phan Thanh Huu and Nguyen Huu Tu. They are being investigated for smuggling, producing and trading in counterfeit goods and illegal invoices and receipts.

Investigators later found the ring had established companies and operated several gas stations to sell their counterfeit products.

Members of the ring used vessels to buy gasoline from wholesalers and then moved the product to a facility on the islet in Vinh Long before using chemicals and solvents to make the 95-octane grade gasoline A95.

The fake fuel was distributed to warehouses across different provinces before being retailed.

According to investigators, around one million liters of fake gasoline were being provided to the market each day.

Since Aug. 20, until the suspects were arrested, the ring had provided 200 million liters of fake gasoline for the market.

Police said the ring is even larger and more sophisticated than the one led by Trinh Suong, a fuel tycoon, who was arrested two years ago for running a fake gasoline manufacturing operation.