Prime Minister Nguyen Tan Dung on Friday ordered related agencies to take urgent steps including checking fuel quality in the market to determine the cause of mysterious vehicular fires.
Dodgy fuel is the latest suspect in more than 100 vehicle fires since early last year, one of which killed a taxi driver this month.
The PM asked the Ministry of Science and Technology to look over Vietnam's set standards for fuel quality, especially regulations concerning the use of combusting additives.
Meanwhile the Ministry of Industry and Trade will make local governments check gasoline quality in their areas and have their market managers shut down any unregistered gasoline retailers.
The Ministry of Transport will check the quality of vehicles on the market, using local market managers and its quality management agency Vietnam Register.
After many vehicle fires, experts including college lecturers have been telling local media that additives such as methanol and ethanol increase fuel combustion.
No official conclusion has been made but a recent investigation by Thanh Nien strengthened the suspicion, when many major fuel trucks were found stopping on their way to gas stations to have fuel siphoned out and replaced by unidentified liquids.
A research by Ho Chi Minh City Polytechnics University, as ordered by the city Department of Science and Technology last weekend, also suggested that the fires were most likely caused by the addition of methanol or ethanol, Tuoi Tre said Saturday.
Dr. Huynh Quyen, director of the university's Petrochemistry Refinery Technology Research Center which conducted the investigation, said fires would occur when vehicle's fuel tanks are down to 5 percent of their capacity.
As the fuel is mixed with methanol, a saturated hydrocarbon mixture would form above the fuel surface inside the tank, which ignites upon hitting colder temperatures outside, Quyen said.
He said the argument is bolstered by the fact that many fires occurred during cold days in Hanoi last year, and that several fires happened before vehicles were even started.
The center has studied 13 gas samples, including mixtures, and adopted the theory after ruling out all other hypotheses such as fuel leakages, short circuits or chemical reactions.
But Quyen said the center needs more time to come to a conclusion.