
Stating that detention of two men by China unjustified, US Secretary of State Mike Pompeo on Monday called for their immediate release.
Two Canadians are charged by China with espionage.
Pompeo said US was "extremely concerned" and that the two men's detention was unjustified.
"These charges are politically motivated and completely groundless," the Secretary of State said in a statement.
Chinese prosecutors announced the charges on Friday against former diplomat Michael Kovrig and businessman Michael Spavor, who were arrested in late 2018.
The two men were detained shortly after Canadian police detained Huawei Technologies Co Ltd's chief financial officer, Meng Wanzhou, on a US warrant.
Canadian Prime Minister Justin Trudeau thanked Pompeo and nations which have recently denounced China's treatment of the two men.
"Our allies around the world are very concerned by the fate of the Canadians because they know very well it could be their turn at some point and we must remain united to deplore these arbitrary arrests," he told a daily briefing in Ottawa.
Trudeau said the cases of the two men and Meng were clearly linked. Earlier in the day China said they were unrelated and repeated calls for Meng's release.