Billionaire Warren Buffett affirmed his support for BYD Co., saying the Chinese automaker part-owned by his Berkshire Hathaway Inc. will be a leader in electric cars. The stock gained the most since July after the company said it has a dealer network for its plug-in hybrids.

Berkshire Hathaway owns 10 percent of the automaker through MidAmerican Energy Holdings Co., based in Des Moines.

“BYD is a young and promising company experiencing dynamic growth,” Buffett said last week during his first visit to the southern Chinese city of Shenzhen, where the manufacturer is based. “BYD will play a leading role in the future.”

BYD’s sales dropped 19 percent in August, and the company has said it may fail to meet a schedule for delivering electric cars to California. BYD said it has signed 30 dealers to market the F3DM plug-in hybrid in 20 Chinese cities.

BYD, founded as a battery maker by China’s richest man, Wang Chuanfu, entered the automobile market in 2003 and began mass production of the world’s first plug-in hybrid five years later. The carmaker plans to start selling the E6 electric car in the United States this year and in Europe next year.