The authorities say sharing a car with a stranger comes with risks that passengers should not ignore.

A man exits the Uber offices in New York, U.S. Photo by Reuters/Brendan McDermid

It's yet another bumpy ride for popular ride-hailing services Uber and Grab.

Their new carpool versions in Viet Nam, UberPOOL and GrabShare, have been blocked by the Ministry of Transport, not long after their summer launch.

Low-cost services that allow drivers to pick up an extra person along the way will create risks for the passenger, the ministry said in a new statement. stopping short of mentioning any such incidents.

The ban is to protect Vietnamese passengers from what could happen, it said.

If Uber and Grab disobey the rule, they will be fined VND4-6 million ($175-260) per ride.

Last month, U.S.-based Uber and Malaysia-based Grab rolled out their carpooling services in Viet Nam, promising to help passengers save 30 percent of payments by splitting the costs.

Uber and Grab entered Viet Nam in 2014. Since then, the two have repeatedly made headlines for regulatory issues.

Exisiting service providers have not been happy. Vinasun and Mai Linh, the two major taxi companies in Viet Nam, blame their business difficulties on Uber and Grab, saying the competition has been "unfair" because the foreign firms are not subjected to strict tax rules.

(Source: VnExpress International)