Three banking and payments associations in China have doubled down on the central bank's 2017 ban on financial institutions and payment firms engaging in cryptocurrency transactions. In a statement, the firms also warn investors against crypto trading, which the statement describes as speculative.

"Recently, cryptocurrency prices have skyrocketed and plummeted, and speculative trading of cryptocurrency has rebounded, seriously infringing on the safety of people's property and disrupting the normal economic and financial order," the three industry bodies said in a combined statement today. Those three bodies are the National Internet Finance Association of China, the China Banking Association, and the Payment and Clearing Association of China.

Though the country's alpha bank has not contributed any new updates to this ban, the People's Bank of China did share the group's latest warning in its official WeChat group.

One of the cryptocurrencies that has recently "plummeted" is of course Bitcoin, the No. 1 cryptocurrency by market cap. Today, Bitcoin is down to $43,000, representing a decline of 22% in the last seven days.

The crypto market correction comes at a time when China has a well-developed central bank digital currency (CBDC) program, which many consider to be world-leading.

Editor's note, May 18 at 11:15am EST: This article has been updated to reflect that the crypto ban on Chinese firms has been in place since 2017. Today, the three payment associations have renewed warnings around crypto speculation.