Canadian Prime Minister Justin Trudeau expressed "extreme concern" after a Chinese court sentenced a Canadian man to death in a retrial ordered not long after the arrest in Vancouver of a Chinese technology executive.

It complicates an ongoing standoff over the arrest of Huawei Technologies' chief financial officer on US charges and the subsequent detention in China of two Canadians.

Trudeau suggested that he sees Robert Lloyd Schellenberg's new sentence as a political move. "It is of extreme concern to us as a government - as it should be to all our international friends and allies - that China has chosen to begin to arbitrarily apply a death penalty."

The arrest of Huawei's Meng Wanzhou has left Canada caught in the middle of a broader conflict between the US and China and sent Canada-China ties to new lows.

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The standoff started with Meng's December 1 arrest in Canada on US charges related to alleged violations of Iran sanctions. Days later, Chinese authorities detained Michael Kovrig and Michael Spavor on suspicion of endangering national security.

Schellenberg, 36, was arrested in 2014 and was later sentenced to a 15-year prison term for smuggling methamphetamine. During a recent retrial prosecutors said new evidence implicated him in a drug trafficking operation. The Chinese Government even invited foreign media to attend his appeal hearing - prompting speculation that Beijing wanted to use the case to exert pressure on Ottawa to free Meng.

"The procedures in Mr Schellenberg's case would be unusual even if he was a Chinese national," said Margaret Lewis, a law professor at Seton Hall University. "The fact that he is a Canadian, combined with the welcoming of foreign media to view court proceedings, makes it downright suspicious."

The Dalian Intermediate People's Court said Schellenberg conspired with three others to pack more than 200kg of methamphetamine in tyres to ship to Australia. Schellenberg has said he was framed. He has the option of appealing again within 10 days. His case is expected to be reviewed by higher courts.