Playing cards in China can legally contain 75 parts per million of the carcinogenic chemical. But one of those tested contained a staggering 612 ppm - seven times the safe amount.
The World Health Organization has previously warned that formaldehyde is one of the main causes of cancer globally.
The Chinese authorities insisted that the makers of the dangerous playing cards will have to recall their products, or face the consequences.
Poker players who have used the affected products have been advised to wash their hands and keep out of reach of children.
