China’s industry regulator has ordered motor companies to inspect the safety of locally made environmentally friendly vehicles, saying the tests are necessary after some battery-powered buses caught fire. Automakers would have until October 20 to report their findings, said the Ministry of Industry and Information Technology in a posting on its website on Thursday. Most Chinese and global automakers on the mainland are developing green cars to meet the country’s fuel economy standards that grow increasingly stricter to 2020. They include BYD, backed by billionaire Warren Buffett’s Berkshire Hathaway, which makes the country’s best-selling “new energy” car, the BYD Qin. The buses that caught fire had safety flaws in their product design and hidden dangers in their everyday use, the ministry said. It gave no details about the incidents, but in April BYD said an electric bus had caught fire in Shenzhen and that the automaker had not manufactured that vehicle. Safety concerns add to the hurdles facing electric car sales in China, the world’s biggest auto market, which also include “range anxiety” owing to the lack of a charging infrastructure. In a separate statement on Wednesday, the ministry said the number of so-called new energy vehicles – a catch-all for electric, hybrid and fuel-cell driven cars – built in China had more than doubled this year, but remained only a fraction of overall vehicle production.