© THE CANADIAN PRESS/HO - International Crisis Group FILE: Michael Kovrig is shown in this undated handout photo.

The detention by China of Michael Kovrig has reached a somber new milestone.

As of Tuesday, it has been 400 days since the Canadian diplomat was detained while on leave from his job and working with the international NGO Crisis Group.

Kovrig was the first of two Canadians detained by China in the days following the arrest by Canadian authorities of Huawei CFO Meng Wanzhou, who is wanted for extradition by the United States. She and her company have since been charged with skirting American sanctions on Iran and stealing corporate secrets.

READ MORE: Judge denies media consortium’s request to broadcast Huawei CFO extradition hearing

Michael Spavor, a Canadian entrepreneur, was detained several days after Kovrig and both have been held without access to legal counsel ever since.

China has been arbitrarily detaining our colleague #MichaelKovrig for 400 days. Michael is a Canadian national. He has yet to see a lawyer or his family. Join our call to #FreeMichaelKovrig ➔ https://t.co/LQTnQ451QR pic.twitter.com/ZEwH5TDDzG — Crisis Group (@CrisisGroup) January 14, 2020

Both Kovrig and Spavor have received only intermittent visits with consular officials during more than a year of detainment and are being subjected to reportedly "harsh" conditions, including Kovrig having his reading glasses confiscated and the lights in their cells being left on at all hours.

Prime Minister Justin Trudeau has repeatedly called for China to release the two Canadians, calling their detentions "arbitrary."

Lawmakers in the U.S., U.K. and dozens of other allied nations have also condemned China's detention of the pair and called for their release.

But China has refused, and late last year formally arrested the two on allegations of endangering national security.

There is no indication of when they could be released, but a Chinese foreign ministry spokesperson told reporters in December that their cases were transferred to prosecutors, hinting at a potential upcoming trial for the two.

READ MORE: Crown says Meng Wanzhou’s alleged actions would be crime in Canada

According to the spokesperson, their cases were sent for “review and prosecution in accordance with the law." In past cases, trials were often carried out behind closed doors and convictions were seen as virtually certain.

Meng, who is currently on bail and living in one of two multimillion-dollar homes in Vancouver, is fighting her extradition to U.S. in British Columbia's Supreme Court -- a battle that could last years.

A hearing is scheduled Jan. 20, focusing on a test of dual criminality -- whether or not the U.S. allegations against Meng would amount to a crime in Canada. On Friday, the Department of Justice filed court documents in support of Meng's extradition to the U.S. on fraud charges.

Allegations against the Huawei CFO accuse her of lying about the Chinese tech company's relationship with the Iran-linked Skycom to HSBC, one of its bankers.

U.S. sanctions against Iran began in 2018 after U.S. President Donald Trump's abandoning of the 2015 nuclear deal, accusing the country of continuing to destabilize the Middle East with proxies.

The detainment of the two Canadians, as well as Meng's extradition case, has largely fractured Canada-China relations.

In the spring of last year, China started blocking canola imports from Canada, citing "hazardous organisms." The block and the arrest of the two Michaels were largely seen as a retaliatory move against Meng's detainment.

A motion in support of creating a special committee to re-evaluate Canada's relationship with China was approved in December.