Their detentions came nine days after Chinese telecom executive Meng Wanzhou was arrested at the Vancouver International Airport and accused of sidestepping U.S sanctions against Iran.
The new State Department warning also follows the arrest of several Chinese nationals in the U.S. on charges of espionage. It has demanded that Canada free her and threatened unspecified consequences if it does not. They could also face "prolonged interrogations and extended detention for reasons related to "state security".
In Ottawa, Prime Minister Justin Trudeau says Meng's case is part of an independent legal process with no outside political influence.
In Vancouver, Meng appears in court, where allegations of fraud are laid out.
This after a Huawei CFO, who awaits extradition to the USA for misleading banks about transactions linked to Iran violating sanctions against that country, is out on bail and living in her Vancouver mansion.
Canadian newspaper, the Globe and Mail, reported that China had detained 13 Canadians since Meng's arrest.
"People who do go to China, I'm hoping they will raise this with their interlocutors to make clear that it is hurting China's image in the world, and it's going to make it harder for some people who want to travel to China", Robert Malley, the Crisis Group's president and a former member of the USA national security council under president Barack Obama, said in an interview Thursday.
The Chinese government has not drawn a direct link between the detention of any Canadian and Meng's arrest.
"The message from Global Affairs Canada. was that it would be better for us to go rather than to cancel", said Cooper.
The warning adds: "China does not recognize dual nationality".
"We don't know what law the Chinese authorities are talking about", said Malley, who once served on U.S President Barack Obama's national security council. In an affidavit submitted for a bail hearing, Meng, 46, details a lifetime of health issues, including thyroid cancer, sleep apnea and high blood pressure.
"Particularly now since President Trump was elected, China wanted to grab this mantle of being the responsible actor on the world stage that was standing up for certain rules".
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Ramsey has been on a long-term contract with the Premiere League club until the final year of his contract this season. We did not win but he is working hard and I am happy. "But above all I want [him to] have his focus on helping us".
"It is not convenient to disclose more information now".
"It's not advancing any objective other than the goal of further raising doubts about China's reliability as a country that's going to follow the rule of law".
"This outnumbers the proportion of Chinese people visiting the United States", Lu said.
The rights of foreign nationals in China have received renewed focus because of public concern over the fate of three United States citizens accused of committing "economic crimes" in the country. He calls on Trudeau to reach out to the highest levels of the Chinese government.
The warning comes after China last month detained two Canadians on charges of activities that endanger China's security.
By way of comparison, there are nearly 900 Canadians in a similar situation in the US.
Canada has sought the support of key allies in pressuring China to release Kovrig and Spavor.
In an interview with The Canadian Press, Trudeau says Canada will shortly be granted consular access to Spavor.
"This doesn't shed much light", said Malley.
December 22: During a visit to Canadian peacekeepers in Mali, Trudeau says countries around the world are "extremely disturbed" by China's detention of Spavor and Kovrig. Joseph Day, was briefed by the Canadian foreign ministry. Spokeswoman Hua Chunying says Canada should "correct its mistakes" and stop acting at the behest of the United States. Kovrig and Spavor remain in custody.
Global Affairs Canada spokesperson Guillaume Berube confirmed the detentions to AFP, adding the figures excluded Hong Kong.
December 30: Australian Foreign Minister Marise Payne says in a statement that her government is "very concerned" about Kovrig's and Spavor's detentions. Prior on Thursday, China's top prosecutor said the two Canadians had without a doubt.