BEIJING: The trial of Michael Kovrig, who has been held in China for more than two years on espionage charges, began in a closed Beijing courtroom on Monday, days after the United States raised concerns over his case at tense talks with China in Alaska.

China arrested Kovrig, a former diplomat, and fellow Canadian Michael Spavor in December 2018, soon after Canadian police detained Meng Wanzhou, the chief financial officer of Chinese tech company Huawei Technologies, on a U.S. warrant.

Beijing insists the detentions are not linked to the detention of Meng, who remains under house arrest in Vancouver as she fights extradition to the United States.

"We've requested access to Michael Kovrig's hearing repeatedly but that access is being denied" over national security reasons, Jim Nickel, charge d'affaires of the Canadian embassy in China, told reporters outside the Beijing court after the trial began. "Now we see that the court process itself is not transparent. We're very troubled by this."

In a show of solidarity, 28 diplomats from 26 countries, including the United States, United Kingdom, Germany, Australia, Netherlands and Czech Republic, turned up outside the Beijing No. 2 Intermediate Court on Monday, which was marked by a heavy police presence.

"(U.S.) President (Joe) Biden and (Secretary of State Antony) Blinken have said that in dealing with the cases of Michael Kovrig and Michael Spavor, the United States will treat these two individuals as if they were American citizens," William Klein, charge d'affaires of the U.S. embassy in China, told reporters as he stood beside Nickel.

"We are here to show solidarity. Arbitrary detention is not the way," another diplomat told Reuters, declining to be named as she was not authorized to speak on the record about the Canadians' trial.

The Canadian side had assembled a group of diplomats to "point fingers" and was "wantonly interfering in China's judicial sovereignty", said Chinese Foreign Ministry spokeswoman Hua Chunying.

More than 50 countries signed a declaration in February to condemn the arbitrary detention of foreign citizens for political purposes.

Some diplomats took off their face masks as they posed for a group photo outside the court, with each shouting out which country they represented to help reporters identify them.

On Friday, Spavor, a businessman, also stood trial in a closed courtroom in the northeastern city of Dandong. That court said it would set a date later for a verdict.

Canadian and other diplomats were not allowed to attend Spavor's trial on what China said were national security grounds, a lack of transparency that Canadian Prime Minister Justin Trudeau called "completely unacceptable".

Observers have said the likely convictions of the two men could ultimately facilitate a diplomatic agreement in which they are released and sent back to Canada.

Chinese courts have a conviction rate of over 99%.

"Michael and Michael Spavor are innocent Canadians caught up in a bigger geopolitical dispute," Kovrig's wife, Vina Nadjibulla, told Reuters.

"Their detention is profoundly unjust and our focus must remain on securing their freedom."

Spavor's trial took place as the United States and China held rancorous high-level talks in Alaska. The United States raised the issue during the talks, a senior Biden administration official said, including its concerns that diplomats were barred from the courtroom in Spavor's trial.