Military headquarters and related agencies in the southern province of An Giang are investigating three trucks and a car which have been found illegally using fake military license plates.
Tran Quoc Hieu, chief of An Giang Military Headquarters' motorbikes inspection department, said the latest suspect vehicle, a seven-seat Toyota Innova, was taken into custody last week.
Driver Hoang Xuan Thang, 48, from Ho Chi Minh City was discovered to be impersonating a military captain and carrying fake documents proving the car was owned by military, according to Hieu.
The trucks, meanwhile, have been impounded since July, he said.
Initial information showed that they were part of a group of up to 10 vehicles using false military-owned license plates to capitalize on the exemption of tolls and other fees when transporting goods.
However, it's still unknown what goods the company was transporting and whether they were legal or not.
Drivers told agencies that the outfit has operated throughout the country for more than one year.
They were told not to drive during rush hours (between 7-8 a.m. and 4-5 p.m.) and park in secret places, according to drivers, adding that they were also given instructions how to deal with military agencies and police when asked about documents.
If they encountered problems, they were told to call a switchboard using two mobile phone numbers, the drivers said.