Hong Kong listed BYD’s share price has risen on speculation that US billionaire investor Warren Buffett intends to raise his stake in the company.

MidAmerican Energy Holdings, a unit of Buffett’s Berkshire Hathaway, bought 10 percent of BYD for US$230m last September prompting a surge in the value of BYD’s shares.

“MidAmerican has always intended to raise its stake in BYD because it believes BYD has good prospects in the development of renewable energy,” BYD Chairman Wang Chuanfu told reporters in Hong Kong on Monday.

BYD is planning a further share offering that would dilute Buffett’s stake and would prompt him to buy more shares, reports say.

BYD also said it expects to sell its e6 electric car in the United States in 2010, a year ahead of schedule.

BYD says its e6 electric car is capable of driving 400 kilometres (249 miles) on a single charge and that it will be launched in the US by the end of 2010.

“e6 will be launched in the United States by the end of 2010 and they are now being tested under U.S. regulations,” Wang said.

The electric cars will be sold in Shenzhen first in the fourth quarter of 2009 and will gradually expand to other cities in China, he added.

Some analysts caution that the firm is noted for its ambitious forecasts and headline grabbing claims.