The missing Interpol chief, Meng Hongwei, who it was revealed on Sunday has been detained in China for 12 days unknown to his family or employer, has resigned from the international police agency.

Interpol said it had received his resignation “with immediate effect” late on Sunday. It was the latest twist in the mystery of Meng’s disappearance last month after he flew from France to China.

In a terse statement on Sunday evening, the Chinese authorities had admitted they were holding Meng under investigation by a new government anti-corruption unit for suspected “violations of the law”.

That admission came shortly after Meng’s wife Grace, said she had received a message from him suggesting he was in danger.

Until the statement from Beijing and the resignation, nothing had been seen or heard of Meng since shortly after he arrived in China on on 25 September.

At a press conference in Lyon, Grace Meng told journalists her husband had sent her an emoji of a knife shortly before he disappeared and that she was convinced it was his way of signalling he was at risk.

She said she had not heard from her husband since the message, sent on 25 September. Normally, they would be in daily contact when he was away working, she said.

Four minutes before he sent the knife image, he sent his wife a text message saying: “Wait for my call.”

On Sunday, a statement from China’s ruling Communist party said Meng was “under the monitoring and investigation” of the new anti-corruption unit, the National Supervision Commission, for suspected serious violations of state law. It gave no further information about the reason for his arrest and detention.

Meng, 64, who is also a senior Chinese security official, had more than 40 years’ experience in criminal justice, particularly in the field of drugs control, counter-terrorism, immigration and border control, before becoming president of Interpol, the international criminal police organisation based in Lyon, in November 2016. He is a senior member of the Communist party.

Interpol has said it is concerned about his apparent disappearance and has made inquiries with China. The organisation’s secretary general, Jürgen Stock, has demanded a “clarification” from Beijing.

“Interpol has requested through official law enforcement channels clarification from China’s authorities on the status of Interpol President Meng Hongwei,” Stock said in a statement. “Interpol’s general secretariat looks forward to an official response from China’s authorities to address concerns over the president’s wellbeing.”

Earlier Interpol had indicated Meng’s disappearance was “for the relevant authorities in France and China” to deal with. France has opened an investigation.

Meng’s wife said he had returned to China, where they are both from, before his disappearance to work, and called on the international community to find her husband.

“I don’t know what has happened to him,” she said. “For as long as I can’t see my husband face to face speaking to me, I can’t be very positive.”

She read a statement in Chinese and English during the press conference, but kept her back to reporters not allowing them to see her face and refused to be photographed, saying she did not want to be identified as she feared for her safety and that of her two children.

Meng’s wife and children had been put under French police protection after they were subject to threats on social media and by telephone, according to France’s interior ministry.

“France is looking into the situation of the president of Interpol and is concerned about the threats his wife has received,” the ministry said in a statement.

The South China Morning Post reported that Meng was under investigation in China for unspecified reasons. Citing an unnamed source, it said Meng had been “taken away” for questioning by disciplinary authorities “as soon as he landed in China”.

Under Chinese law, a suspect’s family and employer must be notified within 24 hours of a detention, except in cases where doing so would hinder an investigation, the paper wrote.

After China admitted it had Meng in custody, the paper quoted the Beijing-based political commentator Zhang Lifan, who said: “I guess something urgent must have happened. That’s why [the authorities] chose to take such immediate action at the risk of losing face on the international stage.”

Interpol said South Korea’s Kim Jong Yang, currently one of the organisation’s four vice-presidents, would become its acting president until Meng’s successor could be appointed at an Interpol meeting in Dubai in November.