OTTAWA -- The former Canadian diplomat detained in China would have been under the close watch of Chinese authorities years ago as he travelled the country and talked to dissidents on behalf of Canada's government, his former boss says.

Michael Kovrig took on political-reporting assignments on highly sensitive subjects, said Guy Saint-Jacques, a former Canadian ambassador in Beijing.

Saint-Jacques said Kovrig tried to "get the pulse" of many groups, such as displaced Tibetans scattered around China and Muslim minorities in the northwestern region of Xinjiang, where Beijing has been accused by the international community -- including Canada -- of mass detentions.

"He went to remote locations trying to meet with people from these communities to try and understand what they were going through, in terms of the challenges they faced, protecting their cultures," Saint-Jacques said in an interview. "So, all of this, obviously, would have attracted the attention of security people."

The former ambassador added that Chinese authorities have extensive files on all diplomats in China, especially those, like Kovrig, who speak fluent Mandarin.

This week, China took Kovrig into custody in a move that came days after Beijing warned Ottawa of severe consequences for its recent arrest of Meng Wanzhou, the chief financial officer of tech giant Huawei. Meng's arrest has enraged China.

Canadian authorities arrested Meng at the request of the United States, which alleges she tried to bypass American trade sanctions on Iran and lied to U.S. banks about her actions.

The Beijing News reported Wednesday that Kovrig "was suspected of engaging in activities that endanger China's national security."

Kovrig gave up diplomatic immunity when he took an unpaid leave of absence from Global Affairs Canada in late 2016 at the end of his posting. A senior government official, briefing reporters Wednesday on condition of anonymity, said he remains a federal government employee.

Saint-Jacques said Kovrig loved China and chose to stay.

In February 2017, Kovrig continued reporting on some of the touchiest subjects involving China after he joined the International Crisis Group as an adviser. His work for the non-governmental organization has covered a range of subjects, including the North Korean nuclear crisis, China's relationship with the U.S. and its expanding presence in Africa.

The senior government official said China confirmed to Canada on Wednesday that the Beijing Bureau of State Security had detained Kovrig. Ottawa, however, doesn't know what the allegations against him are and does not know where he is.

A spokesman for China's Foreign Ministry said earlier in the day that the International Crisis Group, where Kovrig has been a Hong-Kong-based analyst, is not registered in China and alleged its activities in the country are illegal.

Because Kovrig's group is not registered as a non-governmental organization in China, Lu Kang added that "once its staff become engaged in activities in China, it has already violated the law."

Lu also repeated China's demand for Meng's immediate release.

Saint-Jacques says he has a lot of sympathy for Kovrig, whom, based on his experience observing past cases, he believes is already enduring long interrogations by Chinese authorities.

He said they typically take detainees to secret locations, where they are monitored 24 hours a day with the lights always kept on. Saint-Jacques said Kovrig will likely @face sleep and food deprivation as well as interrogations at all hours.

"They try to create as much psychological pressure as possible to make you crack," said Saint-Jacques. "This will go on until they are satisfied, until they extract a confession. We have known people who are ready to admit to anything just to get out of there."

He added that Kovrig likely won't be officially charged and arrested until after this process, which can take months or more.

"In the Chinese system, once you are officially charged -- in 99.9 per cent of the cases you are also found guilty," he said. "So, the odds are against you."