Chinese police patrol in front of the Canadian Embassy in Beijing on Dec. 13. (Greg Baker/AFP/Getty Images)

China has significantly upped the ante in its diplomatic standoff with Canada, not just detaining two Canadian citizens but accusing them of serious crimes — charges that could result in their imprisonment for months with no outside contact.

For starters, China could hold Michael Kovrig, an analyst with the International Crisis Group think tank, and Michael Spavor, who runs tours and promotes investment in North Korea, in “black jails” for as long as six months without allowing them access to lawyers or their families.

“Isolating someone in that way for an extended period of time, holding them incommunicado without any oversight, it’s the perfect environment for torture and other illegal treatment of a suspect,” said Joshua Rosenzweig of Amnesty International. “It’s a way to exert physical and psychological pressure to get someone to confess.” 

This would give the Chinese government plenty of time to decide how to proceed.

After a Canadian court granted bail in the case that apparently led to the standoff — the arrest of Meng Wanzhou, the chief financial officer of Chinese electronics giant Huawei Technologies — the United States and Canada now have three months to act.

Meng, the daughter of Huawei’s founder, was detained Dec. 1 in Vancouver at the request of the United States, which is seeking her extradition to face charges of violating American sanctions on Iran. She was freed on bail Tuesday while the legal process continues.

China is outraged over Meng’s detention and continues to call for her complete release. But rather than risk derailing efforts to resolve the trade war with the United States, it is directing its ire at Canada.

Foreign Ministry spokesman Lu Kang confirmed Thursday that the two Canadians were ­detained Monday, Kovrig in Beijing and Spavor in Dandong, on the Chinese border with North Korea. 

The Canadian Embassy in Beijing has been informed, he said, but he declined to say whether the two have been allowed to consult lawyers. “I can tell you that their legitimate rights and interests have been safeguarded,” Lu said.

It initially appeared that the men might be held for violating China’s strict new laws governing the operation of foreign nongovernmental organizations. When first asked about Kovrig’s case, Lu said that the Crisis Group was not registered in China and that Kovrig was therefore operating illegally.

But Lu’s confirmation Thursday that both men were detained by local departments of the Ministry of State Security on “suspicion of engaging in activities that endanger national security” demonstrated that their cases were much more serious than a breach of the NGO law.

China defines “endangering state security” in broad terms to include criticism of the ruling Communist Party and advocating for the independence of Tibet or Taiwan. It is not in itself a crime but rather a category of offenses that include espionage, inciting subversion, treason, separatism and trafficking in state secrets to foreign entities.

“If this was simply about a breach of the NGO law, I do not believe that the Ministry of State Security would be involved,” Rosenzweig said. “This is looking like the beginning of a criminal investigation to me.”

In Ottawa, Andrew Scheer, the leader of the opposition Conservatives, said there is a “direct link” between the detentions of the Canadians and the legal proceedings against Meng.

The Ministry of State Security deals with political security and espionage and has had increasing power under President Xi Jinping, who has taken aggressive measures to stifle freedom of speech and civil society since he became China’s leader in 2013.

“The cases of the Canadians are reminders that, as the Chinese government becomes more repressive under Xi Jinping, the impact of its abuses is going to be increasingly felt beyond China’s borders,” said Maya Wang of Human Rights Watch. 

While the investigation is going on, the men can be held under what China calls “Residential Surveillance at a Designated Location.” This is essentially a legalized form of enforced disappearance, human rights advocates say.

China has a playbook for this situation. 

When Peter Dahlin, a Swede who had been helping train lawyers and promote the rule of law in China, was detained in January 2016, he was held in solitary confinement in a secret jail and had no access to a lawyer.

He later described being held in a padded room and questioned for hours each day. He was subjected to a form of torture — having fluorescent lights left on constantly so he could not sleep — and he could hear a colleague being beaten in another room. 

After persistent questioning about his group’s activities, he was forced to deliver a confession that had been scripted for him and to apologize for “hurting the feelings of the Chinese people.” He was then deported.

There is an even more apt precedent.

In 2014, two Christian aid workers from Canada who had been living in China for 28 years were suddenly arrested by the Ministry of State Security in Dandong and charged with “suspicion of stealing and spying to obtain state secrets.” Julia Garratt spent six months in detention before being released on bail — but forced to remain in China — while her husband, Kevin Garratt, was imprisoned for two years.

It later transpired that Canada had arrested Su Bin, a Chinese citizen who was wanted for extradition to the United States to face charges of stealing military information.

It was clear to the Garratts’ lawyer, James Zimmerman, that they had been arrested to try to stop Canada from extraditing Su to the United States. After Su gave up his fight and was extradited, the Garratts were released within months.

Zimmerman sees echoes of their case in the detention of Kovrig and Spavor. “Even if there is a legal basis for the detentions, like a violation of the foreign NGO law, the timing clearly reflects that they have been caught up in a police dragnet for what looks like political leverage,” he said.

 One of the Chinese government’s most aggressive explainers, Hu Xijin, editor of the Global Times newspaper, is not even trying to pretend that the two cases are not linked.

“Please note the two Canadians detained in China are under investigation in accordance with the law. This includes the possibility they may be released at some time,” he wrote on Twitter. “Westerners who were detained by China in the past were deported soon. Hope this time there is reason to be faster.”

Yang Liu In Beijing and Amanda Coletta in Toronto contributed to this report.