OTTAWA -- Prime Minister Justin Trudeau says the government is using public and private measures to secure the release of two Canadians detained in China for 18 months, who on Friday were formally charged with espionage in the politically charged case.

Trudeau said he was "very disappointed" with the charges Chinese prosecutors unveiled, while Deputy Prime Minister Chrystia Freeland described feeling personally angry at the news.

Former diplomat Michael Kovrig was charged in Beijing on suspicion of spying for state secrets and intelligence. Businessman Michael Spavor was charged in Dandong near the North Korean border on suspicion of spying for a foreign entity and illegally providing state secrets.

Speaking at a press conference in Chelsea, Que., just north of the national capital, Trudeau said the only reason the two are being detained is because of independent judicial proceedings involving Meng Wanzhou, a top executive at Chinese tech giant Huawei who is fighting an extradition request to the United States.

Trudeau said aside from public statements, there is "action behind the scenes in very direct and firm ways" to secure their release.

"We have developed a certain expertise in what has worked to get Canadians home in very difficult circumstances over the past years," Trudeau said.

"In the case of the two Michaels, I can say that we are using a wide range of public and private measures to ensure that everything is being done to get these Michaels home."

The two have been held since December 2018, shortly after Canadian authorities arrested Meng at Vancouver's airport. U.S. authorities want her extradited over allegations she circumvented American sanction on Iran.

The daughter of Huawei's founder and the company itself deny any wrongdoing. She remains out on bail as hearings at the B.C. Supreme Court continue in her case. A judge rejected the first set of arguments from her lawyers late last month in a bid to set her free.

"We will not, and must not, and cannot interfere in the independence of our judiciary in this country," Trudeau said.

"The Chinese authorities have directly linked the case of the two Michaels to the judicial proceedings against Ms. Meng, which is extremely disappointing because for us ... there obviously are no links except in politics."

Wrapped up in the case is Huawei's bid to be a player in Canada's 5G network, which was put in doubt after Bell and Telus announced partnerships with the Chinese company's European rivals.

The Liberals have yet to decide whether Huawei will have a role in building the network.

The United States has warned Canada and other allies that it will limit sharing intelligence with countries that have Huawei equipment in their 5G networks -- citing its potential use for spying by China, an allegation Huawei denies.

The charges against Spavor and Kovrig were announced Friday by China's highest prosecutor's office in brief social media posts. Chinese foreign ministry spokesperson Zhao Lijian said each is charged with "secretly gathering state secrets for overseas forces with particularly serious consequences."

"The facts are clear and the evidence solid and sufficient," Zhao told reporters at a daily briefing, without providing further details.

The International Crisis Group, where Kovrig worked at the time of his arrest, said the diplomat regularly interviewed Chinese officials to accurately reflect their views in his reports and had a constructive relationship with Chinese officials.

"This is yet another arbitrary and baseless step in a case that has been arbitrary and baseless from day one," the group's chief executive, Robert Malley, said in a statement. "Michael was not endangering China's security: everything he was doing was in the open and well known to China's authorities."

Kovrig and Spavor have had no access to lawyers or their families as of May, with the exception of a phone call the Chinese embassy said Kovrig was allowed to make to his sick father in mid-March. Consular visits have also been suspended because of the COVID-19 pandemic.

Speaking at a midday press conference on Parliament Hill, Freeland said it was essential to restore consular access to the two men.

"They are a priority for Canadian foreign policy in general, they are a priority for our government in general, they are not forgotten and we are going to continue to work very, very hard for their release," she said.

Conservative Leader Andrew Scheer said the government's "naive approach to Beijing" has hampered efforts to release Spavor and Kovrig.

"This case should be being dealt with at the highest levels. But Justin Trudeau has repeatedly refused to intervene," Scheer said in a statement.

This report by The Canadian Press was first published June 19, 2020.

-- With files from the Associated Press