From small scooters to luxury SUVs, dozens of vehicles have burst into flames in Vietnam this year, triggering panic among motorists who say the government is failing to respond.

Officials and state media have variously blamed poor maintenance, engine problems or even rats gnawing through cables for the fires, which have destroyed buses and reduced motorbikes to charred metal frames.

But anger is growing among sceptical drivers who say poor quality fuel is the real culprit and fear lives will be lost before the government acts.

There have been 324 incidents of burning vehicles reported in 2010 and 2011, according to public security ministry figures quoted in a recent report on the government's website, the majority of which ‘have not been solved satisfactorily,’ officials have told local media.

Since the start of this year, 65 cases of burning vehicles have been reported nationwide, from a 70-year-old man on his scooter to a famous actress in Ho Chi Minh City driving a Nissan saloon.

While not many major injuries have been reported so far, standard insurance policies in the communist country typically exclude fire damage.

Vietnam's public, wary consumers after a string of food scandals, including the 2007 discovery of formaldehyde in the national dish, pho noodle soup, say the cause of the fires is clear and the government is failing to respond.

"It's the quality of the petrol. Everyone knows that. The authorities know that. But they haven't investigated (the source of the poor-quality fuel) and ordinary people are in panic," driver Nguyen Quy Nhuong, 52 said.

Some 85 per cent of respondents to a survey on the popular VNExpress website said low-quality fuel was behind the mysterious fires, with many suggesting cheap chemicals are being mixed into petrol by unscrupulous dealers.

Petrol prices soared nearly 30 per cent last year, outpacing 18 percent inflation and creating an incentive for traders to cut expensive fuel with cheaper substances.

Vietnam boasts rich offshore crude reserves but has to import most of its oil and petroleum products as it has only one refinery in operation.

Last year, imports were worth $9.9 billion, up 62 per cent from 2010, and in the first two months of this year, Vietnam spent roughly $1.27 billion on importing petroleum products.

This is likely to increase further as the country moves firmly into middle income status and more Vietnamese buy motorbikes and cars.

Some 13 corporations have government licences to import fuel, which is then distributed to about 13,000 petrol stations nationwide.

The end price of 22,900 dong ($1.09) per litre ($4.12 per US gallon) is kept artificially low by subsidies and dealers regularly complain it is hard to turn a profit.

Suspicions run high that petrol tanker drivers or fuel station owners are cutting fuel to make more profit - which many say is the real cause of the fires.

"We are absolutely not putting any additives into the imported petroleum," said Vuong Dinh Dung, CEO of the Military Oil and Gas Corporation.

"The sales agents are the one to take charge of ensuring the petroleum standards," he told local media after one of the army-owned company's distributors was caught selling adulterated petrol.

A sample was found to have too much methanol in it and the distributor was fined.

The government carries out spot checks across the distribution chain but experts say it is an uphill struggle, and the small fines imposed are seen as unlikely to deter tampering.

"It it really difficult to control the quality of fuels used in Vietnam," said Huynh Quyen, director of the Refinery and Petrochemicals Technology Research Center, who is investigating the spate of engine fires.

"We are investigating whether fuel problems could have caused the fires," he said, adding that the research would not be made public before a scientific conference scheduled for April because of the sensitivity of the issue.

Deputy Prime Minister Hoang Trung Hai said this month that "market control agencies (must) pay more attention to the sales and use of additives," in petroleum, according to a report on the government's website.

"The quality of petroleum continues to be the key focus for quality checking," the March report continued.

But until the problem is sorted out, some have sarcastically suggested rejecting modern transport in favour of time-tested conveyances.

"The safest means of transport here would be to go back to carriages drawn by cows, buffalos or horses," one reader commented on the VNExpress website.

The government response has been vague, with Transport Minister Dinh La Thang saying his ministry "would take charge" of the situation this year, but not offering any details of what this would entail.

So until a solution is found, drivers such as 35-year-old office worker Nguyen Vu Ninh are "praying it will not happen to me."