BEIJING — Robert Lloyd Schellenberg, the Canadian man found guilty of drug trafficking in China, will appeal the death sentence ordered by a Chinese court this week, the law firm representing him said Tuesday, as the strained relationship between Canada and China spiraled deeper into crisis.

The appeal would launch a legal process that could take months. After an appeals judge makes a ruling, China’s highest court would still need to make a final decision before Schellenberg is put to death.

“Of course we’re going to appeal. How can we accept the death penalty?” said Shang Baojun, a lawyer at the Mo Shaoping firm, which represents Schellenberg and other high-profile figures in political cases.

The two nations’ relationship has rapidly deteriorated since Canada detained Chinese technology executive Meng Wanzhou in Vancouver last month at the behest of the United States. The Huawei chief financial officer is wanted in the United States to face fraud charges related to Huawei’s business dealings with Iran.

Shortly after Meng’s seizure, which Beijing views as unlawful, China detained two Canadians on national security charges and retried Schellenberg in unusually public fashion. Western analysts said the moves amounted to a retaliatory pressure campaign, which Beijing staunchly denies.

Speaking for the first time about the case, Canadian Prime Minister Justin Trudeau implied Monday that Schellenberg’s death sentence was politically motivated and “arbitrarily applied.” Hours later, Canada issued a travel advisory for China, warning Canadians that they could face “arbitrary enforcement of laws” in that country.

Chinese Foreign Ministry spokeswoman Hua Chunying shot back Tuesday, likening the Canadian travel warning to “a thief calling out another thief.”

“It’s actually Canada, not China, that has arbitrarily detained a foreign citizen based on so-called ­legal reasons,” Hua said, referring to Meng, who is out on bail in Vancouver awaiting the outcome of her extradition hearings. China also issued a travel advisory of its own, warning citizens about the dangers of traveling to Canada.

Schellenberg was retried Monday after an appeals judge ruled in December that his previous sentence — 15 years imprisonment for attempting to ship 222 kilograms of methamphetamine out of northern China — was too light. Prosecutors said at the December hearing they had found new evidence implicating Schellenberg in an international trafficking operation, and therefore demanded a harsher sentence.

The December hearing came weeks after Meng’s arrest, prompting speculation that Schellenberg’s retrial may have been politically influenced.

“The charges [at the retrial] were the same as the first trial, so I don’t think the sentence can be increased,” Zhang Dongshuo, Schellenberg’s lawyer, said by telephone after the retrial. “Even if they prove that he’s part of an international crime ring, the penalty cannot be raised because the allegations were the same.”

Zhang added that he saw Schellenberg Tuesday after the death sentence, and he looked “fine.”

Through weeks of mutual recriminations and allegations of hostage-taking, the dispute has centered on the Shenzhen-based telecommunications equipment maker, which has long been a source of pride for China — as well as a source of concern for Western cybersecurity and defense officials, who warn that Huawei is inextricably beholden to China’s ruling Communist Party.

Even though U.S. officials and legal experts say that Meng’s extradition warrant was legally justified, China has viewed the detention of its star executive as symbolic of a broad, U.S.-led conspiracy against its growing tech industry — and against China’s very rise. After Poland arrested a Chinese Huawei executive last week on espionage charges, many Chinese social media users rallied to the company’s cause, with some joking that China should find a Polish drug trafficker to sentence, much like it did a Canadian.

As the sniping between Beijing and Ottawa continued Tuesday, Meng’s father, reclusive Huawei founder Ren Zhengfei, made a rare public appeal for her freedom as he distanced Huawei from the Chinese government. It was the first time he had spoken to foreign media in years.

“I love my country. I support the Communist Party. But I will not do anything to harm the world,” he told a small group of reporters in southern China, according to Bloomberg News. “I don’t see a close connection between my personal political beliefs and the businesses of Huawei.”

Huawei’s travails, Ren said, were a “sesame seed” in China’s broader trade conflict with the United States. 

He appeared to strike a conciliatory note as he praised President Trump’s tax overhaul agenda. Ren offered that Huawei could pull back from its aggressive global expansion if that would make it seem less of a threat to Washington.

“If they don’t want Huawei to be in some markets, we can scale down a bit,” he was quoted as saying, referring to the United States. “As long as we can survive and feed our employees, there’s a future for us.”

Yuan Wang in Beijing contributed to this report.