Apple said Monday that it will investigate claims that an iPhone may have electrocuted and killed a 23-year-old woman in western China, only months after the company’s warranty policies attracted the ire of Chinese media and regulatory groups.

China’s state-run Xinhua News Agency reported over the weekend that Ma Ailun, a former flight attendant, died after answering a call on a charging iPhone. The report — along with the social-media postings of Ma’s relatives — quickly went viral in China, the second-largest market for Apple iPhones. A local investigator told the Wall Street Journal that the woman suffered “an obvious electronic injury.”

“We are deeply saddened to learn of this tragic incident and offer our condolences to the Ma family,” Apple said in a statement. “We will fully investigate and cooperate with authorities in this matter.”

The company declined to elaborate on the incident or what may have caused it. It is unclear whether the phone was to blame. China’s consumer safety agency has warned of an electrocution risk from unregulated mobile-phone chargers, which are common in China.

On China’s Twitter-like Sina Weibo, however, Ma’s family members offered their own theories: “I . . . hope that all of you will refrain from using your mobile devices while charging,” read one post attributed to Ma’s older sister and translated by Xinhua.

The incident is the latest setback for Apple’s China operations, which have faced repeated controversies even as the market comes to represent a greater share of the tech giant’s operations. This year, Apple Chief Executive Tim Cook issued an apology and changed Apple’s warranty policy after a lengthy assault by the Chinese media, which complained that the policies were unfair. And reports of abuse and unfair labor conditions at Apple suppliers remain a salient issue in China, said Michael Palma, a consumer electronics analyst at market intelligence firm IDC.

Case in point: On the same weekend it published reports of Ma’s electrocution, the Xinhua agency also ran a dramatic profile of a Foxconn worker who “casts a cold eye over the iPhones that pass through his hands each day.”

“The Apple brand still carries the value in China that it carries in the U.S.,” Palma said. “But preserving that image is what’s driving Apple’s quick response — they’ve been very proactive in trying to demonstrate that they’re concerned” about Chinese consumers.

That concern underscores exactly how important the Chinese market has become to companies such as Apple. Until recently, China was perhaps best known as a supplier, not a consumer, of luxury tech products such as the iPhone.

But in the past fiscal year, China, Taiwan and Hong Kong accounted for 14 percent of Apple’s global sales, and that share is expected to grow, said Brian Colello, an analyst at Morningstar. (Apple’s North and South American sales, by comparison, represented 37 percent of the world total.) China is the world’s largest smartphone market, with Apple, Samsung and homegrown brands such as Lenovo and Huawei duking it out for market share.

None of those brands have been immune to these types of incidents. Colello pointed out that last week, a woman in the United Arab Emirates complained that her Samsung Galaxy S4 caught fire while charging overnight.

“These types of stories tend to pop up when there are tens, if not hundreds, of millions of devices used by consumers,” he said.

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