THE wife of missing Interpol director Meng Hongwei has revealed he sent her a photo of a knife shortly before he vanished after landing in China.

French cops opened an investigation after Meng's other half reported him missing, police sources said on Friday.

Making her first public comments on the mystery surrounding Meng’s whereabouts, Grace Meng told reporters in Lyon, France on Sunday she thinks the knife was her husband’s way of trying to tell her he was in danger.

She says she has had no further contact with him since the message that was sent on Sept. 25. She says four minutes before Meng shared the image, he had sent a message saying, “Wait for my call.”

It comes as Interpol released a statement saying Meng resigned as head of the organisation.

It said: "Today, Sunday 7 October, at the Interpol General Secretariat in Lyon, France received the resignation of Mr Meng Hongwei as President of Interpol with immediate effect."

It is unclear what the circumstances are surrounding Meng's resignation and if it is connected to him being investigated by China over suspected violations of the law.

Interpol added South Korean national Kim Jong Yang would become the acting president until a new president is appointed at the November 18-21 meeting in Dubai.

Meng's wife, who lives in Lyon, where Interpol is based, contacted the authorities after not hearing from her husband since he travelled to China in late September.

Meng used to be Vice Minister of Public Security in China, according to Interpol's website.

His run as Interpol's director began in November 2016 and is due to run until 2020.

The 64-year-old who is also a vice-minister at China’s Ministry of Public Security, was “taken away” for questioning by discipline authorities “as soon as he landed in China” last week, the SCMP reports.

It is not yet clear why Meng is being investigated or exactly where he is being held.

Human rights groups expressed concern at the time that Beijing might try to use Meng's position at the body to go after dissidents abroad.

Beijing has tried for many years to enlist the help of foreign countries to arrest and deport back to China citizens it accuses of crimes including corruption and terrorism.

Interpol told The Sun Online in a statement: "Interpol is aware of media reports in connection with the alleged disappearance of Interpol President Meng Hongwei.

"This is a matter for the relevant authorities in both France and China.

"The Secretary General is the Organisation's full time official responsible for the day to day running of Interpol.

"Interpol's General Secretariat headquarters will not comment further."

Established in 1923, Interpol is a global organisation that seeks to help police forces around the world cooperate and coordinate.