Police in the north central province of Nghe An arrested four people for producing and installing computer chips that allowed fuel pump operators to cheat their customers.
On Monday, an anonymous police source said they'd discovered doctored chips in 11 gas stations during joint-raids organized with the Department of Science and Technology between October 9 and November 7, Tuoi Tre newspaper reported.
The investigative squad arrested Nguyen Son Hai, 41, on November 5 and recovered 23 chips from his residence.
Hai said he bought the chips from Le Van Toan, 34, who surrendered himself and a laptop he used to program the chips to police on November 12.
Hai said he installed the chips for six fuel companies for VND5 million (US$235) per chip.
Police followed the money all the way to two chief suppliers Tran Le Duc, 35, in the central resort town Nha Trang, and Bui The Ai, 45, in Nghe An’s capital town Vinh on November 15.
During raids on the two men's residences, police recovered 190 chips.
The producers said they have been providing the chips for more than six years, helping gas stations skim between 4 and 11.6 percent off the top of each transaction.
Nguyen Manh Ha, deputy chief inspector at the Nghe An Department of Science and Technology, told Tuoi Tre the retailers will be fined between VND70-100 million ($3,290-4,700).
The department is cooperating with the police to investigate further.