China is demanding that Canada release Huawei Technologies chief financial officer Meng Wanzhou, whose arrest is now being characterized as kidnapping in Beijing.

The Vancouver airport arrest of Ms. Meng at the request of U.S. authorities in the midst of a contentious trade war has jolted financial markets and thrust Ottawa into the middle of a fraying relationship between the world’s two most powerful economies.

It also made Canada the object of Chinese fury.

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“Without any solid evidence, the Canadian and U.S. governments trampled on international law by basically ‘kidnapping’ Chinese citizen Meng Wanzhou,” Mei Xinyu, a research fellow with an institute under the Ministry of Commerce, wrote in the pages of the Global Times, a nationalist tabloid published by the Communist Party.

Tom Fowdy, a British political analyst writing for the state-run CGTN network, called Canada a party to a “political hostage-taking by the Trump administration.” More than 10,000 commenters piled on to the Twitter-like Weibo page of the Canadian embassy in China, calling Canada an indecent nation, a thug, a jackal and worse.

And the Chinese Foreign Ministry demanded Canada release Ms. Meng, accusing Ottawa of abusing one of its citizens.

“Detaining a person without providing an explanation has undoubtedly violated her human rights,” Chinese Foreign Ministry spokesman Geng Shuang said on Thursday. The Chinese government “has made clear our solemn positions to the U.S. and Canada,” Mr. Geng said. Neither Canada nor the United States has yet to give “any explanation on the reason for the detention,” he added.

Huawei has said Ms. Meng was arrested at the request of the United States, which is seeking her extradition. The Americans allege she violated U.S. trade sanctions against Iran.

The United States has warned the Chinese government could use Huawei technology to threaten the national security of countries that install its devices.

Ms. Meng, 46, is the daughter of Ren Zhengfei, the former army engineer who founded Huawei and led its immense growth. Huawei is now China’s biggest private company, with a payroll of 180,000, and the world’s second-largest maker of smartphones.

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It has been one of China’s most prominent corporate successes, a telecommunications titan that embodies President Xi Jinping’s desire to make his country into a powerful force for innovation and global leadership. Half the company’s revenue come from international markets.

In China, Ms. Meng’s arrest was seen as a new step in a wide-reaching Washington campaign to stymie those aims and cripple the prospects of a company that has pushed ahead in the race for next-generation 5G mobile-communications technology.

“This is like a sudden attack,” said Li Daokui, a prominent scholar and director of the Centre for China in the World Economy at Tsinghua University.

“Imagine that Facebook’s Sheryl Sandberg was detained in Japan or Korea at the request of the Chinese government. Imagine what the political response would be in the U.S.”

Ms. Meng’s arrest also raised broader fears about the future of Huawei and the prospects for resolution of a damaging trade dispute between China and the United States.

Ms. Meng was taken into custody on the same day Mr. Xi and U.S. President Donald Trump agreed to a 90-day negotiation in hopes of resolving the trade frictions that have led the United States to impose tariffs on US$250-billion worth of Chinese goods.

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Mr. Li said he was “optimistic” those talks would continue. “The stakes are too high for the two sides to throw away the 90-day deal,” he said.

But if China’s wrath over the Huawei arrest “continues to ferment, it will ruin the progress the two countries have made,” said Chen Qi, a resident scholar at the Carnegie-Tsinghua Center for Global Policy.

It’s also “obvious that Huawei and all related firms will fall under more severe inspection if they want to step into foreign markets,” he said.

The United States can only seek extradition of people wanted in criminal matters. If the extradition is successful, prosecutors will then have to convince a U.S. court of her guilt beyond a reasonable doubt, a higher standard than that required in civil cases.

“It’s a sign they have a very serious matter,” said Julian Ku, a professor of constitutional law at Hofstra University. Such a case is much harder to prove than “if they just wanted to cut Huawei out of the market,” he said.

The United States, Australia and New Zealand have all moved to block Huawei’s 5G technology. Canada and Britain have not done so, although Britain’s BT Group said it would remove Huawei equipment from sensitive parts of its 4G network. Important portions of Huawei’s 5G research have been done in the Ottawa area.

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Some faulted Canada for siding with the United States in the arrest of Ms. Meng.

“It’s a very unwise thing the Canadians are doing,” said Victor Gao, a director at the China National Association of International Studies, who warned about the dangers of being an “accomplice” of the United States.

“If a couple of Canadian nationals are arrested somewhere as a bargaining chip, it may not be surprising,” he said.

In a sign of the anger at Canada, Zuo Chuanchang, chief research fellow with the Academy of Macroeconomic Research at the National Development and Reform Commission, declined an interview with The Globe and Mail, saying, “you are the ones who arrested her and caused this. I refuse to talk to Canadian media.”

The Canadian government has in recent months renewed efforts to build ties with China amid a broad bid to diversify markets for trade. Finance Minister Bill Morneau was recently in Beijing for meetings in which, according to a Canadian government statement, “the two sides reaffirmed their commitment to deepening and expanding the Canada-China economic and trade relationship.”

But the arrest of Ms. Meng complicates matters. China will “have to do something concrete to show their displeasure,” said Phil Calvert, a former Canadian diplomat who is now a senior fellow with the China Institute of the University of Alberta.

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“No matter how much the Canadian side says that we’re just following legal procedures, Chinese officials probably will believe that the arrest was directed or tacitly supported at very senior levels,” he said.

Still, he said, the fact Canada has not followed allies in blocking Huawei’s 5G technology may cause China to moderate its response – and any anger at Ottawa is likely to subside if Ms. Meng is extradited to the United States and is no longer in Canada.

With reporting by Alexandra Li