A logo of BYD is painted inside an assembly line of the automobile maker in Shenzhen, China May 25, 2016. REUTERS/Bobby Yip

SHANGHAI (Reuters) - China’s new-energy auto firms saw shares surge in Monday morning trade, extending recent strong gains, after a government official said over the weekend that China had begun looking at a ban on traditional petrol-engine cars.

Chinese electric-car maker BYD Co Ltd, backed by U.S. billionaire Warren Buffet, saw its shares jump, while lithium products maker Jiangxi Ganfeng Lithium Co Ltd rose more than 5 percent to a record high.

China has begun studying when to ban the production and sale of petrol cars, the official Xinhua news agency reported on Sunday citing a vice minister who it said predicted “turbulent times” for automakers as they were forced to adapt.

Xin Guobin, vice minister of the Ministry of Industry and Information Technology, did not say when the world’s largest auto market would implement such a ban. Britain and France will ban new petrol and diesel cars from 2040.

Xin said the ministry had started research and will look to draw up a timeline with relevant departments.

An index tracking new-energy vehicles makers shot up nearly 4 percent early on Monday to a 14-month high, having gained over 20 percent this year.

BYD jumped 4.1 percent and 5.9 percent in Shanghai and Hong Kong respectively. Ganfeng Lithium was up over 5 percent, having seen its shares rocket nearly 300 percent so far this year.