Fierce competition among China's leading EV makers has intensified, with a long-running dispute between BYD and Great Wall Motor over emissions compliance escalating after Geely joined in to criticise BYD's aggressive price cuts.

The row dates back to 2023, when Great Wall Motor reported BYD to Chinese regulators, alleging that its two best-selling hybrid models failed to meet emissions standards.

The issue re-emerged last month when Great Wall’s chairman, Wei Jianjun, expressed concerns about the ongoing price war and confirmed that the regulatory probe was still active.

BYD dismissed his remarks on the industry's health as "alarmist" but did not comment on the emissions issue. At the time, BYD rejected the claim and said its vehicles met China's emission standards.

On Saturday, Geely’s vice president, Victor Yang, publicly backed Great Wall’s claims at an auto conference in Chongqing, stating that Geely had conducted its own emissions tests and reached the same conclusions.

"Wei Jianjun is a genuine, honest person and is our industry's whistleblower," Yang said in videos of his speech posted online by The Paper and other local media outlets.

Great Wall Motor's claims concern BYD's use of non-pressurised fuel tanks in its Qin Plus and Song Plus plug-in hybrids, which let the liquid inside evaporate more rapidly than in pressurised ones.

BYD's general manager of branding and public relations, Li Yunfei, responded to Geely's comments on Sunday on his Weibo account, saying that the non-pressurised tanks used in its cars between 2021 and 2023 were compliant with the regulatory requirements at the time but added that BYD had since changed them due to customer complaints.

Li's Weibo post was no longer there on Monday, although Reuters could not verify the reason for this and the company did not immediately reply to a request for comment.

Great Wall Motor did not immediately respond to a request for comment on Monday, while Geely referred Reuters to the videos posted online of Yang's speech and declined to provide additional comment.

China's Ministry of Industry and Information Technology, one of the regulators involved in the emissions probe, did not immediately respond to a request for comment.

The escalating feud comes as China's EV market faces intense competition as BYD's recent price incentives, which reduced the starting price of its cheapest model to 55,800 yuan ($7,771.05), triggered a broader sell-off in auto stocks.

Following this, MIIT called for the sector to halt its price wars and summoned automakers to a meeting last week, two sources familiar with the matter said. The meeting was first reported by Bloomberg.

Dealers have also urged automakers to stop dumping inventory on them.