Interpol has said that its president Meng Hongwei has resigned, as the mystery surrounding the missing official deepened.

The announcement came after Beiing announced that Meng was under investigation in China on corruption charges, while his wife Grace Meng told reporters on Sunday that he had sent her an image of a knife, which, she believes, could signal that he is in danger.

This photo shows the last message sent by Meng Hongwei to his wife Grace. The message at 12:26 on September 26 says “wait for my call”. Four minutes later, he sent the photo of the knife. Earlier that day, she had sent him a photo of two animal figurines, one of a bear and another of a horse, meant to represent their two children; one of them loves horses, she said, and the other “looks like the bear”. AP

Meng has been reported missing, by his wife, since September 25, while on a visit to his native China.

In her first public comments since Meng went missing, Grace told reporters in the French city of Lyon, where Interpol is based, that she hasn't heard from her husband since September 25 when he sent her the image of the knife.

She said that four minutes before Meng shared the image, he had sent a message, saying, 'Wait for my call.'

Meng Hongwei has been missing since September 25. AP

Interpol said on Saturday that it has made a formal request to China for information about Meng.

Interpol did not clarify why Meng had quit as president of the agency's executive committee, only saying the resignation would be effective immediately. It added that the senior vice-president of its executive committee, Kim Jong Yang of South Korea, would become acting president.

The disciplinary organ of China's ruling Communist Party said on Sunday night that Meng, China's vice-minister of public security, is 'currently under the monitoring and investigation' of China's new anti-corruption body for legal violations. The party's watchdog for graft and political disloyalty said on its website late on Sunday that Meng is 'suspected of violating the law and is currently under the monitoring and investigation' of China's new anti-corruption body, the National Supervision Commission.

Chinese authorities said they are investigating the former Interpol president for bribery and other crimes and indicated that political transgressions may have also landed him in trouble. In a statement posted on a government website on Monday, the authorities said Meng was being investigated due to his own 'willfulness and for bringing trouble upon himself'.