By Trefor Moss

SHANGHAI-- Tesla Inc., hit by a widespread outcry over its handling of consumer complaints in China, has issued a public apology and pledged to set up a customer-satisfaction unit as the electric-car maker seeks to overcome its latest stumble in the fast-growing market.

A protest by an aggrieved Tesla customer at the Auto Shanghai expo on Monday sparked an online backlash against the U.S. car maker. The protester alleged that faulty brakes on her family's Model 3 sedan had caused a crash that left her parents needing hospital treatment earlier this year. Last month, in response to earlier protests by the same person, Tesla issued a statement saying that the woman's father had been speeding at the time of the crash, citing a police report.

"We apologize for failing to resolve the problem of the car owner in time," Tesla said late Tuesday local time on its official account on China's Twitter-like Weibo platform. "We will try our best to learn the lessons of this experience."

Hours earlier, the Central Political and Legal Affairs Commission, a high-level Communist Party body that oversees the country's legal apparatus, accused Tesla of arrogance and of endangering Chinese consumers by selling defective products.

"Tesla has to face up to the torment of its Chinese customers" and stop "pretending to be oblivious to hidden dangers of which it's well aware," the commission said in a post on social-media platform WeChat.

In its apology, Tesla pledged to establish a unit that would focus on delivering customer satisfaction. Tesla said it obeys decisions of government departments, respects consumers, and actively cooperates with all investigations.

Its statement didn't directly address the allegations of faulty brakes or other quality shortcomings.

Tesla has faced mounting customer complaints in China over quality issues in recent months. Regulators in Beijing summoned Tesla for a rare public rebuke over its quality record in February, prompting the company to promise to make improvements. Last month, Chief Executive Elon Musk was forced to reassure Chinese officials and consumers that Tesla cars couldn't be used to spy on China, following a government move to ban military personnel and staff from key state-owned companies from driving its cars in case the vehicles posed a security risk.

China is a fast-growing market that Mr. Musk has said will become the company's largest. China hosts Tesla's only operational plant outside the U.S.

Though the auto-show protester, a Ms. Zhang, from China's central Henan province, was bundled away by security guards and later detained by the police, videos of her standing atop a Model 3 sedan and railing against the company went viral on the Chinese internet. The images amassed more than 150 million views within a few hours and fueled a passionate online debate about Tesla's treatment of local consumers and about the quality of its cars.

Ms. Zhang has demanded a full refund, according to Tesla.

Grace Tao, a company vice president who is one of Tesla's top executives in China, told local media at the show Monday that the company had previously tried to resolve its dispute with Ms. Zhang, but that the company "cannot meet unreasonable demands." Ms. Zhang, she said, was a "professional" protester who may have been acting on behalf of individuals who wanted to cause trouble for Tesla.

That stance prompted Xinhua, a state-run news agency, to publish a commentary on Tuesday that questioned whether Tesla had handled the complaint with decency. "As a star brand in the auto industry, Tesla's own standards for quality and its commitment to users ought to live up to the market's expectations," it said.

Ms. Zhang couldn't be contacted for comment.

In its apology Tuesday, Tesla thanked customers for their tolerance.

"We will keep listening to customer feedback, keep optimizing the customer experience, and keep serving every customer well," it said.

Tesla sold 35,478 locally built Model 3 and Model Y cars in China last month, according to the China Passenger Car Association--by far its best monthly performance in the country as it ramps up output from its Shanghai plant.

Write to Trefor Moss at Trefor.Moss@wsj.com

(END) Dow Jones Newswires

04-21-21 0545ET