China's biggest maker of electric vehicles, BYD, posted strong financial results in the first quarter of this year, fueled by ongoing growth in the sales of new-energy vehicles.

The company’s profit rose seven-fold during the quarter to about 750 million yuan ($111 million). Operating income rose 22.5% to 30 million yuan.

The firm sold 73,172 new-energy vehicles — cars that use pure electricity, hybrid or hydrogen technologies — in the first three months, up 147% year-on-year.

The Shenzhen-based company, which also sells fossil-fuel cars and makes handset components, is backed by U.S. investor Warren Buffett. Buffet’s gamble over a decade ago on what was then an unknown battery maker has paid off, as China invested heavily in renewable energy and BYD has matured into a competitive full-fledged carmaker. Berkshire Hathaway Energy, controlled by Buffett's holding company Berkshire Hathaway, holds 8.25% of BYD.

However, Beijing has begun reducing its assistance to new-energy vehicle-makers, with plans to completely phase out subsidies it had been giving by 2020.

BYD’s Hong Kong-listed shares opened at HK$56 on Monday, up 4.7% from their previous close. Its Shenzhen-listed shares opened up 1.3%.

Related: China’s Cut to Electric-Car Subsidies Is the Biggest in Five Years