Prime Minister Justin Trudeau says he is "very concerned' about China's stance following reports coming out of Beijing this morning accusing two Canadian men of working together to steal state secrets.

In a short statement posted online, the ruling Communist Party's Central Political and Legal Affairs Commission accused Canadian citizen Michael Kovrig of stealing state secrets passed on to him from another detained Canadian, Michael Spavor.

"We are obviously very concerned with this position that China has taken," Trudeau told reporters during a funding announcement in Charlottetown this morning.

"The safety and security of Canadians is always of first order for this government. That's why we've been engaging and standing up for the two Canadians who have been arbitrarily detained by China from the very beginning."

Businessman Spavor and Kovrig, a Canadian diplomat on leave, were arrested in early December shortly after Canada arrested Huawei Technologies executive Meng Wanzhou, who faces extradition to the United States.

China has demanded repeatedly that Meng be released and has lashed out publicly against Canada throughout the extradition process. Last week, Beijing cited the ongoing SNC-Lavalin controversy as leverage in Meng's case, questioning the state of judicial independence in Canada.

While China has invoked national security to justify detaining the Canadian men, Monday's statement marks the first time Chinese authorities have gone into more detail.

The Chinese Central Political and Legal Affairs Commission's statement said Kovrig had often entered China using an ordinary passport and business visas, "stealing and spying on sensitive Chinese information and intelligence via a contact in China."

"Spavor was Kovrig's main contact and provided him with intelligence," the commission added, without giving details.

The next phase in the judicial process for Kovrig and Spavor will start soon, the statement said.

"China is a country with rule of law and will firmly crack down on criminal acts that severely undermine national security," it said.

No link to Meng's arrest, China says

This latest development is likely to put further pressure on the damaged diplomatic relationship between Ottawa and Beijing.

Canada issued an authority to proceed on Friday, formally commencing an extradition process in Meng's case. While Canada says China has made no specific link between the detentions of the two Canadians and Meng's arrest, experts and former diplomats say they have no doubt Beijing is using the detentions to retaliate.

David Mulroney, a former Canadian ambassador to China, called it a game of tit-for-tat.

"Well, sadly, this is to be expected," he said on Monday. "At each step China then acts in a kind of grotesque parody of what Canada has done."

Kovrig works for the International Crisis Group (ICG), which focuses on conflict resolution and has denied any involvement in espionage.

"Michael's work for Crisis Group has been entirely transparent and in the open as all who follow his work can attest. Vague and unsubstantiated accusations against him are unwarranted and unfair," said ICG director Hugh Pope in a statement to CBC News.

In this Jan. 29, 2019, file photo, Huawei chief financial officer Meng Wanzhou leaves her home to attend a court appearance in Vancouver, British Columbia. Canada said Friday, March 1, 2019, it will allow the U.S. extradition case against Wanzhou to proceed. (Darryl Dyck/Canadian Press)

Canadian diplomats have been allowed to see the two men. However, sources familiar with the case have said Kovrig has not been allowed access to lawyers or family members, unlike Meng.

Ramping up the pressure

Mulroney said Chinese officials likely will ratchet up pressure on Kovrig and Spavor going forward.

"I think many efforts will be made to encourage them to confess to something that they didn't do," he said.

"They will be asked repeatedly about conversations they had, people they met, and they'll be told that if they confess to something, they may be able to expect a degree of leniency."

Canada arrested Meng on Dec. 1 as she was changing planes in Vancouver, at the request of the United States, which has filed sweeping charges against Huawei and Meng that paint the company as a national security threat.

Meng has been charged with bank and wire fraud in connection with alleged violations of U.S. sanctions on Iran. She is free on bail and denies the charges against her.

Over the weekend, she filed a civil claim against members of the Canada Border Services Agency (CBSA), the RCMP and the federal government, alleging "serious breaches of her constitutional rights" when she was detained, searched and interrogated at Vancouver International Airport in December.

The claim says Meng is seeking damages for "misfeasance in public office and false imprisonment."

During a briefing with reporters on Monday, Chinese Foreign Ministry spokesperson Lu Kang once again urged Canada to release Meng and "avoid making more mistakes."

Kang accused both the United States and Canada of abusing their bilateral extradition treaties.

"This is a serious violation of the legitimate rights and interests of Chinese citizens. It is also a serious political event," he said.

Meng's next scheduled court appearance is on Wednesday.