Canada has repeatedly denounced the prosecutions of Kovrig and Spavor as arbitrary and demanded their release.
Chinese prosecutors said on Friday they have charged two detained Canadians for suspected espionage, indictments that could result in life imprisonment, in a case that has driven a diplomatic wedge between Ottawa and Beijing.
Two separate notices published by the Supreme People's Procuratorate on Friday said the two Canadians have been formally prosecuted by branches in Beijing and Dandong, with their respective cases entering a phase of "legal review".
Former diplomat Michael Kovrig and businessman Michael Spavor were arrested in late 2018 on state security charges, soon after Canadian authorities arrested Huawei Technologies Co's chief financial officer, Meng Wanzhou, in Vancouver on a USA warrant.
The pair were detained shortly after Huawei executive Meng Wanzhou was arrested in Canada on a U.S. warrant, in what is widely believed to have been a retaliatory move from China.
Last month, Huawei's Meng lost a legal bid to avoid extradition to the United States to face bank fraud charges.
Kovrig and Spavor have not been allowed to see a lawyer or members of their family despite being detained for more than 18 months.
In a major setback for Meng's fight to avoid extradition, a Canadian judge last month ruled that the US charges against Meng could also constitute crimes in Canada.
Their detention is widely understood as an attempt to pressure Canada to release Meng, chief financial officer at Chinese tech giant Huawei.
China has denied any explicit link between her case and the lengthy detention of the two Canadian men, but outside experts see them as tied and Chinese diplomats have strongly implied a connection.
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The daughter of Huawei's founder and the company itself deny any wrongdoing.
The next round of legal arguments is set to focus on whether Meng's arrest was unlawful and whether the USA records of the case contain misstatements or omissions.
"These Canadian citizens are being held for no other reason than the Chinese government being disappointed with the independent proceedings of the Canadian judiciary".
In her decision, Justice Heather Holmes wrote that "as a matter of law, the double criminality requirement for extradition is capable of being met in this case".
In May this year, a court in Canada ruled that proceedings to extradite Meng to the United States could go ahead.
Foreign Affairs Minister Francois-Philippe Champagne responded in turn by calling for the release of the two "arbitrarily detained" Canadian men. Zhao gave no details.
The Liberals have yet to decide whether Huawei will have a role in building the network.
At the same time, the embassy said Kovrig and Spavor were being provided with better food to strengthen their immunity against the novel coronavirus.
Bell Canada announced that Sweden-based Ericsson will be its supplier and Telus Corp. later announced that it had also selected Ericsson and Nokia.
"We will continue to use all of our expertise to return these two Michaels to Canada".