Hong Kong (CNN) More than a hundred former diplomats, academics and activists have written an open letter to Chinese President Xi Jinping calling for the immediate release of two Canadians detained in China.

Michael Kovrig and Michael Spavor were arrested late last year, amid rising diplomatic tensions between Ottawa and Beijing following the detention of Huawei executive Meng Wanzhou in Vancouver on December 1.

Meng, daughter of the Chinese tech giant's founder, is likely to face extradition to the United States over allegations she helped Huawei dodge US sanctions on Iran.

Beijing has fiercely objected to Meng's capture and subsequent house arrest. Within weeks of her arrest, the two Canadians -- former diplomat Kovrig and businessman Spavor -- were detained on suspicion of "activities that endangered China's national security."

"We, the undersigned scholars, former diplomats, and others with an interest in understanding China and building bridges, are deeply concerned about the recent detentions," the signatories to the open letter said.