The detention of Mr. Meng, 64, is an audacious step by the party, even by the standards of the increasingly authoritarian system under the leadership of President Xi Jinping. China has sought legitimacy and a leadership role in international organizations, and Mr. Meng’s appointment in November 2016 as the president of Interpol, the first Chinese head of the global policing agency, was seen by many as a significant step in that direction. His detention undermines that campaign.

Mr. Meng’s appointment “was considered quite an achievement for China and a sign of its international presence and growing influence,” said Julian Ku, a professor at Hofstra University’s Maurice A. Deane School of Law, who has studied China’s relationship with international law.

While China may have had its eye on placing its citizens in other top posts at prominent global organizations, “the fact that Meng was ‘disappeared’ without any notice to Interpol will undermine this Chinese global outreach effort,” Mr. Ku said. “It is hard to imagine another international organization feeling comfortable placing a Chinese national in charge without feeling nervous that this might happen.”

The announcement of Mr. Meng’s detention came hours after his wife, Grace, told reporters in Lyon, France, that before her husband had vanished on a trip to China, he had sent her a phone message with an emoji of a knife.

She interpreted the knife image to mean “he is in danger,” she said in a brief statement to reporters on Sunday in Lyon, where the two were living and where Interpol is headquartered.