Thirteen people were trapped in an illegal coal mine in southwest China after it flooded, state media reported Wednesday, in the latest mining accident to hit the nation.

The flood happened early Wednesday morning in Anshun City in Guizhou province, when 20 people were working in the pit, the official Xinhua news agency reported.

Seven escaped but the others were trapped and chances of surival were slim due to the amount of water in the pit, Xinhua quoted the local rescue headquarters as saying.

A preliminary investigation found the mine did not have a work safety certificate and its production permit had expired, according to the report.

The mine's legal representative, Zhang Ping, was taken into police custody.

Nearly 3,800 people died in Chinese coal mines last year, according to official figures. However, independent monitors say the real figure is much higher as many accidents are covered up.