Ministry of Public Security inspectors said on Thursday they had found evidence that 23 power agencies were selling toxic waste instead of treating them in line with regulations.
According to the Environmental Crime Police Division C36B, the agencies, mostly power companies in the Mekong Delta, had violated environmental laws by auctioning toxic waste, such as used oil, for the last several years.
Buyers, meanwhile, were usually companies that were not licensed to trade in toxic wastes, the one-year inspection found out.
However, Phan Huu Vinh, deputy head of C36B, said they couldn't impose any punishment on the violators except for warnings, given that detected sales were conducted between two to three years ago.
Under environmental laws, fines have to be imposed on violations within two years of the events.
The Ministry of Natural Resources and Environment categorizes used oil, such as transformer oil, as toxic waste.
Polychlorinated biphenyls, or PCBs, found in the oil are known pollutants and hazardous to human health.