(CNN) A second Canadian has been detained in China in a potential act of retribution that threatens to escalate the diplomatic dispute between Washington, Beijing and Ottawa following the arrest of a Chinese Huawei executive in Canada.

On Thursday, China's Ministry of Foreign Affairs confirmed that Canadians Michael Spavor and Michael Kovrig are "being investigated" on suspicion of "activities that endangered China's national security."

Canada's Foreign Ministry reported Thursday that both Spavor and Korvig were detained in China.

Speaking at a daily press briefing in Beijing, Chinese Foreign Ministry spokesman Lu Kang said authorities had taken "compulsory measures" on the two men on Monday and that both cases remain under investigation.

When asked by CNN, Lu would not specify what "compulsory measures" means nor would he be drawn in to whether the two men are still in custody. The term "compulsory measures" is generally used to refer to detention in China.

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