Beijing (CNN) Relations between Beijing and Ottawa are at crisis point after a Canadian man was sentenced to death by a Chinese court , a former Canadian ambassador to China told CNN.

Canada's foreign ministry issued a travel warning late Monday to its citizens in China over "the risk of arbitrary enforcement of local laws." It came in the wake of the death sentence handed to Robert Lloyd Schellenberg during a one-day retrial in the city of Dalian.

Schellenberg had initially appealed a 15-year prison sentence for being an accessory in a plot to smuggle more than 222 kilograms (489.4 pounds) of methamphetamine from the northeastern port city to Australia in November 2014. But during the retrial, the court sided with the prosecution, which claimed to have uncovered new evidence proving Schellenberg's principal role in the case.

The decision comes against the backdrop of a spiraling diplomatic dispute between the two countries following the arrest of Meng Wanzhou, a senior executive from the Chinese tech firm Huawei, on December 1 in Vancouver.

Meng, the daughter of the company's founder, is likely to face extradition to the United States over allegations she helped Huawei dodge US sanctions on Iran.

Beijing has fiercely objected to Meng's capture and subsequent house arrest. Within weeks of her arrest, Chinese authorities detained two Canadians -- former diplomat Michael Kovrig and businessman Michael Spavor -- on suspicion of "activities that endangered China's national security."

Former Canadian ambassador to China, Guy Saint-Jacques, told CNN on Tuesday that he believed China was making an example out of Schellenberg.

"We're going through a crisis," said Saint-Jacques, who was based in Beijing from 2012 to 2016. "What is peculiar is the timing and this was done, I think, after the arrest of Ms. Meng."

Chinese Foreign Ministry spokeswoman Hua Chunying said Tuesday that the Canadian travel warning was unnecessary, adding Canadians were safe in China, "as long as they abide by Chinese laws."

"I think Canada's travel warning is like 'thieves yelling out thieves' because it is actually Canada, not China, that has arbitrarily detained a foreign citizen based on so-called legal reasons," she said.

In response, China issued its own travel warning Tuesday for Canada, citing the "arbitrary detention" of a Chinese citizen for a third country as a reason for the notice.

The Chinese state-run Global Times tabloid published an editorial Monday accusing Canada of hypocrisy and arguing that "many" foreign citizens had been sentenced to death in recent decades for smuggling drugs in China.

"The trial of Schellenberg shows China practicing its judicial sovereignty. Western media should cover this case responsibly to avoid misleading potential offenders of Chinese law. Schellenberg's trial is not a 'political verdict,'" the piece said.

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Appeal expected

Schellenberg is now expected to appeal his conviction, a member of his legal team told CNN on Tuesday.

Gary Schellenberg, Robert's uncle, said his family is devastated by the ruling.

"We don't know how much to talk about right now and what to say. We are all very heartbroken right now, and we are all in shock. We are just overwhelmed," he told CNN on Monday.

Schellenberg's family said in a statement after the ruling that they were asking all Canadians to "stand with us and pray for the safe return of our loved one."

Canadian Prime Minister Justin Trudeau told CNN partner CTV News that the ruling was of "extreme concern" to his government, "as it should be to all our international friends and allies."

"China has chosen to begin to arbitrarily apply the death penalty in cases facing, as in this case facing a Canadian," he said.

China was strongly dissatisfied with Trudeau's remarks, Chinese Foreign Ministry spokeswoman Hua said Tuesday.

"We urge Canada to respect the rule of law, respect China's judicial sovereignty, stop its wrongdoing and stop making irresponsible remarks," she said.

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A bargaining chip for Beijing

Concerns that Schellenberg could be used as a bargaining chip in the detention of Meng come amid an ongoing pushback from Chinese officials and state-run media outlets.

In a video posted to Global Times' website in December, editor Hu Xijin said if Canada extradited Meng to the US, "China's revenge will be far worse than detaining a Canadian."

This was followed by an opinion piece published on January 9 by China's ambassador to Canada, Lu Shaye, in which he accused the Canadian government of "white supremacy" over its handling of the case.

"I have recently heard a word repeatedly pronounced by some Canadians: bullying. They said that by arresting two Canadian citizens (Kovrig and Spavor) as retaliation for Canada's detention of Meng, China was bullying Canada," the ambassador wrote last Wednesday in The Hill Times, a Canadian publication.

"To those people, China's self-defense is an offense to Canada. If someone slaps you on your left cheek, give him your right cheek, they told us. But I have never seen them doing as they said."

Human rights activist Michael Caster told CNN Schellenberg's sentencing was politically motivated.

"Everything about Robert Lloyd Schellenberg's case screams retaliatory and arbitrary, from the odd step for China of inviting foreign media to his appeal hearing to the almost immediate announcement of his capital sentencing," Caster said Tuesday. "It is clear China wants the world to see what it is doing in this case."