A Chinese court is expected to deliver a verdict Wednesday in the trial of Canadian businessman Michael Spavor, detained on spying charges his country insists have been "trumped up".

Spavor was detained in 2018 along with compatriot Michael Kovrig in apparent retaliation for Canada's arrest of Huawei executive Meng Wanzhou on a US extradition warrant.

Relations between the two countries have hit rock bottom, with Ottawa and Beijing trading allegations of the politicisation of legal cases against each other's nationals.

The Spavor verdict is due a day after a Chinese court upheld the death sentence of another Canadian citizen on a drug smuggling conviction.

Spavor and Kovrig -- a former diplomat -- were formally charged with spying in June last year, and their separate trials took place in March.

The pair have had almost no contact with the outside world since their detention.

Virtual consular visits resumed in October after a nine-month hiatus, which authorities said was due to the coronavirus pandemic.

Canadian diplomats were barred from entering Spavor's trial in Dandong this March, which lasted less than three hours.

A man walks inside the detention center where Canadian businessman Michael Spavor is being held on spying charges in Dandong, China
A man walks inside the detention center where Canadian businessman Michael Spavor is being held on spying charges in Dandong, China AFP / Noel Celis

His family have maintained he was innocent of the accusations against him, saying he had done much as a businessman to "build constructive ties" between Canada, China and North Korea.

While Beijing has insisted the detention of the two Canadians is lawful, it calls Meng's case "a purely political incident".

Spavor's verdict comes a week after fresh hearings in the Meng case began in Vancouver following nearly three years of court battles and diplomatic sparring.

Her hearings are due to end on August 20 but no decision is expected for several months.

Observers say the likely verdicts and sentences for both Canadians will track Meng's trial.

Canada's former ambassador to China, Guy Saint-Jacques, told AFP that Spavor would likely receive a "harsh sentence" as Chinese leaders seek to pressure Canada into returning Meng.

Associate Professor Lynette Ong of the University of Toronto added: "If we see this as the beginning of a political bargaining process, the Chinese (are) likely to want to appear strong in the first instance."

China's judicial system convicts most people who stand trial.