A charging unit for Hong Kong’s electric taxis, manufactured by BYD Co. -- the Chinese electric carmaker that counts U.S. investor Warren Buffet as a shareholder -- nearly caught fire at a taxi parking lot, raising enough product safety concern to pull the company’s stock price down more than 9 percent in Hong Kong on Thursday.

The company told the Wall Street Journal it was investigating the incident involving the BYD e6 with the local owner of the taxis and chargers, Link Management Ltd.

Link said it was suspending operations of its 10 electric taxis until it could work with the company and local government to find out what happened and how to avoid another incident.

BYD said on its official Weibo micro-blog account that the “partial melting” and smoking of the charging unit was caused by a technical flaw in that charger.  

China has been pushing for expanded use of electric vehicles in a drive to reduce air pollution and demand for gasoline, but like in the U.S., sales of electric vehicles in China have been disappointing so far.

On May 1, BYD announced it was building a plug-in electric bus factory in Lancaster, Calif., with the aim of eventually producing 1,000 units a year.

In May 2012 a BYD e6 electric taxi caught fire after an accident in Shenzhen, near Hong Kong, that killed three passengers and raised alarm over the safety of electric vehicles containing large lithium ion battery packs. The accident involved a vehicle rear-ending the taxi at more than 100 miles per hour, sending the vehicle spinning into a tree that split the back end of the car open all the way through the rear seats, according to the New York Times. The battery pack of this model is located under the rear seats.

BYD responded by saying any car in that kind of accident could catch fire. In 2011, the battery pack of a Chevy Volt hybrid ignited, but U.S. regulators have since declared the Volt to be as safe as any gas-powered vehicle.