Former U.S. national security adviser H.R. McMaster said Thursday China's treatment of two detained Canadians is a telling example of how China is a threat to the liberal international order.

The retired lieutenant general who served as President Donald Trump's national security adviser said at the Munk debate in Toronto Thursday that China's communist party exposes the nature of their system every day and it's time for people to wake up.

"Our free and open societies are under attack by an authoritarian closed model. A model that not only is affecting the Chinese people by extinguishing their rights, their rights to free speech, their rights to privacy but it is also affecting other nations of the world," McMaster said.

"Ask your two Canadian citizens who were essentially taken hostage and are still in captivity, one of them a former diplomat whose child was born a few weeks ago," he said.

China detained former diplomat Michael Kovrig and entrepreneur Michael Spavor on Dec. 10 in an apparent attempt to pressure Canada to release a top Chinese tech chief executive who is facing fraud charges in the U.S.

Canada arrested Huawei chief financial officer Meng Wanzhou Dec 1.

Spavor and Kovrig haven't been given access to lawyers.

Meng is out on bail awaiting extradition hearings and living in her Vancouver mansion.