Jacob Wallenberg, the chairman of Investor AB, told a Swedish newspaper that "stopping Huawei is definitely not good." An Investor spokeswoman declined to comment on the Chinese media's reports. She said China is the second- or third-largest market for many of Investor's holdings, and that the company supported Mr. Ekholm's leadership at Ericsson.

Mr. Ekholm said he responded to the Sweden Huawei ban and Beijing's threats on behalf of only Ericsson, not the Wallenbergs. In interviews with journalists in both Europe and China, he called the Swedish ban of Huawei and ZTE unfair. Visiting Sweden at the time, Mr. Ekholm also scheduled a meeting with lawmakers to criticize what he considered a ham-fisted handling of the Huawei decision.

From late October to early December, Mr. Ekholm sent Sweden's foreign-trade minister, Anna Hallberg, a series of messages. He texted her a link to a news article with the headline: "China's ambassador: We might punish Ericsson." He noted how Sweden handled the situation differently than other countries: "The decision the government has supported singles out our Chinese competitors in a way no other EU country has done," he wrote.

At another point he asked: "Shouldn't you talk to PTS?" referring to the independent telecom regulator by its initials.

"I really am trying to do what I can, Börje," Ms. Halberg wrote back. In a written statement, she said she took no measures to influence the regulator's decision and that Sweden is working to strengthen economic ties with China.

Huawei asked Mr. Ekholm to help find legal counsel in Sweden, according to a person familiar with the matter, but Mr. Ekholm said in a text to Ms. Hallberg that he couldn't find a lawyer to take up the cause. "There are plenty of cowards unfortunately," he wrote.

The text messages became public after a records request by Swedish newspaper Dagens Nyheter. "The SMSes were merely a way to document what had happened," Mr. Ekholm now says. "I didn't want [Swedish politicians] to come back to me and tell me, 'You never said anything.' "

Some Ericsson employees, meanwhile, felt their CEO crossed a line by actively helping a rival, according to a person familiar with the matter, especially considering China's own restrictions on foreign businesses. All but about 10% of the Chinese telecom-equipment market is controlled by Chinese players, largely Huawei.

Mr. Ekholm said he expects and respects different opinions from a company with 100,000 employees.

Mr. Ekholm says that while Chinese sales are important to Ericsson, he was primarily concerned about the less-visible effects of being shut out of the country, where 5G rollout has outpaced the U.S. and Europe. By being on the ground, learning how 5G works in the field, "we get to be at the forefront," Mr. Ekholm says.

He says he has been surprised that politics has become part of his daily life. "I didn't think about this at all when I took this job," he says. "We find ourselves in an epicenter of activity, geopolitically, which I think was certainly not the main reason I signed up and have no real background in."

--William Boston contributed to this article.

Write to Stu Woo at Stu.Woo@wsj.com

(END) Dow Jones Newswires

03-31-21 1141ET