China's top electric carmaker BYD announced a record quarterly profit on Monday, underscoring the firm's growing dominance in a high-tech sector that is fiercely contested by both domestic and foreign competitors.

The Shenzhen-based firm posted a profit of 10.4 billion yuan (US$1.42 billion) for the July-September period, its highest-ever earnings during a single quarter and up 82 percent on-year, a statement to the Hong Kong Stock Exchange showed.

The figure was in line with BYD's previous forecast of between 9.55 billion yuan and 11.55 billion yuan in quarterly earnings.

BYD's cumulative net profit for January-September reached 21.4 billion yuan, more than doubling on-year and surpassing last year's total annual earnings of 16.6 billion yuan.

Electric vehicle demand has soared in recent years in China.

BYD, whose investors include US investment titan Warren Buffet, wants its sales to be dominated by electric and hybrid vehicles by 2035.

Earlier this year, BYD became the first global manufacturer to pass the five million milestone in electric vehicle production, crowning itself "the world's leading manufacturer of new energy vehicles and power batteries".

Originally specialising in the design and manufacture of batteries, the company diversified into the automotive sector in 2003.

Many foreign automotive leaders -- including Tesla, BMW, Mercedes and Audi -- depend on BYD for their batteries.

The firm still faces stiff competition from several local brands, including XPeng, Nio and Geely. (AFP)