Image copyright Reuters

China has rejected accusations from Canada that it is arbitrarily applying a death sentence to a Canadian convicted of drug smuggling.

The foreign ministry told Canadian PM Justin Trudeau to "stop making such irresponsible remarks", accusing Canada of "double standards".

Robert Lloyd Schellenberg was initially given a 15-year jail term in November.

But on Monday a court increased this to the death penalty, saying the original sentence was too lenient.

The ruling is likely to worsen a diplomatic row between the countries, which has been escalating since Canada arrested an official of China's Huawei telecoms giant last month.

China has expressed anger at the arrest of Meng Wanzhou, the daughter of Huawei's founder, on suspicion of using a subsidiary company to evade US sanctions on Iran between 2009 and 2014.

She was detained at the request of the United States.

Ms Meng, 46, denies the charges. She was granted bail shortly after her arrest, but remains under constant surveillance and must wear an electronic ankle tag.

Denying that Beijing had politicised Schellenberg's case in response to Ms Meng's arrest, Chinese foreign ministry spokeswoman Hua Chunying urged Canada to "respect China's judicial sovereignty".

"The comments from the Canadian government are full of double standards," Ms Hua said, adding: "The Canadians are the ones who have arbitrarily arrested somebody," in an apparent reference to Ms Meng.

Foreign Minister Chrystia Freeland told reporters on Tuesday that Canada had formally appealed for clemency for Schellenberg. She also struck a softer tone when she spoke of the "very important and long-standing ties" between both countries.

"It is true that this is a difficult moment," she told a news conference in Quebec. "The best thing for both Canada and China... is to get past these current difficulties."

Why was Schellenberg given a death sentence?

The Canadian, who is believed to be 36, was arrested in 2014 and accused of planning to smuggle almost 500lb (227kg) of methamphetamine from China to Australia.

Schellenberg, who has previous drugs-related convictions in Canada, has denied the charges against him, saying he entered China as a tourist and was framed.

Mr Trudeau has condemned the latest ruling, saying: "It is of extreme concern to us... that China has chosen to begin to arbitrarily apply the death penalty."

How often are foreigners executed in China?

Drug dealing is punishable by death in China, and at least a dozen foreigners have been executed for drug-related offenses. Many more are on death row.

Image copyright AFP Image caption Schellenberg was tried at the Dalian Intermediate People's Court

However, the execution of Westerners is less common. One of the most high-profile cases involved British man Akmal Shaikh, who was executed in 2009 despite claims he was mentally ill and an appeal for clemency from the UK prime minister.

His family said that Shaikh had never received a mental health assessment and that judges at an appeal hearing laughed openly at Shaikh as he pleaded for his life.

Is the death penalty a political move?

China has argued that Schellenberg's death sentence was not political.

However, some analysts have argued that both the timing, and the publicity given to Schellenberg's retrial has been unusual.

It took a Chinese court two and a half years to hand down Schellenberg's initial sentence of 15 years - but the retrial lasted just a day.

China also worked hard to push Schellenberg's case to international prominence, taking the highly unusual step of inviting foreign journalists into the court, the BBC's John Sudworth in Beijing reports.

Image copyright Reuters Image caption Meng Wanzhou is the daughter of Huawei's founder

Donald Clarke, a specialist in Chinese law at George Washington University, said that Schellenberg's death sentence appeared to be "an unprecedented step in China's diplomacy".

"I have seen cases I considered unjust before, but I cannot recall a previous case that looked so clearly unconnected to the defendant's guilt or innocence," Prof Clarke told the BBC's Chinese service.

Schellenberg's lawyer, Zhang Dongshuo, told Reuters that his client's sentence should not have been increased, because no new evidence had been presented at the retrial. He intends to appeal.

Chinese state media have reacted angrily to claims the death sentence is linked to Ms Meng's case.

Nationalist newspaper Global Times called it "unreasonable speculation" in Western media, arguing it showed "rude contempt toward Chinese law".

However, back in December, the editor of the Global Times had warned that China would "definitely take retaliatory measures against Canada" if Ms Meng were not released, adding: "If Canada extradites Meng to the US, China's revenge will be far worse than detaining a Canadian."

China was previously accused of tit-for-tat action, after it detained two other Canadian citizens in the weeks following Ms Meng's arrest.

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