French police are investigating the disappearance of Interpol chief, Meng Hongwei, who was reported missing after travelling from France to his native China, and they have placed his wife under protection after threats, the interior ministry said on Friday.
Meng was last seen leaving for China from Interpol's headquarters in Lyon, southeast France, in late September, the source said.
It says the agency "looks forward to an official response from China's authorities to address concerns over the president's well-being". France has launched its own investigation.
But news of his absence was swiftly followed by speculation that the 64-year-old Meng - who also serves as a vice-minister of China's Ministry of Public Security - had been swept up in Beijing's secretive anti-corruption campaign.
So far, Chinese authorities have not made an official statement in this regard.
China has not commented officially on Meng's disappearance. His family members last heard from him before he left for China on September 29.
He added that China was likely to "brush off" any political damage that it would cause to Beijing's involvement in worldwide bodies.
It is not clear why Meng - the first Chinese president of Interpol - would be under investigation.
Following the appointment, critics suggested that Meng's appointment gave Beijing a chance to enlist more worldwide help in tracking down alleged economic criminals, including corrupt officials, targeted by President Xi Jinping's anti-corruption campaign.
Interpol has downplayed the concerns, saying the president has little influence over the organisation's day-to-day operations, which are handled by secretary-general Stock, a German.
Such actions would be contrary to Interpol's mission statement: "Action is taken within the limits of existing laws in different countries and in the spirit of the Universal Declaration of Human Rights".
Also, at one time, China prized Mr Meng's lofty position at Interpol so it was hard to imagine what he had done for Beijing to willingly, and publicly, forfeit the top job at Interpol. His term in Lyon runs until 2020.
Al Jazeera's Adrian Brow, reporting from Beijing, said China's silence is a "reflection of how sensitive this case is".
In 2014, China worked through Interpol to issue notices for 100 Chinese corruption suspects who fled overseas.