Binance users traded cryptocurrency-related assets worth $90 billion in a single month in China, where such trading has been illegal since 2021, The Wall Street Journal reported, citing internal figures, and current and former employees of the exchange.

The transactions made China Binance's biggest market by far, accounting for 20% of volume worldwide, excluding trades made by a subset of very large traders, according to the report published on Tuesday, without specifying the month in which the transactions were made.

Binance's origins lie in China, though the world's largest crypto exchange withdrew from mainland China in 2017 during a regulatory crackdown.

"The Binance.com website is blocked in China and is not accessible to China-based users," a spokesperson for the exchange told Reuters when contacted for comment on the report.

The exchange has also been under the scrutiny of U.S. regulators including the Commodity Futures Trading Commission (CFTC) and the Securities and Exchange Commission (SEC).

The CFTC sued Binance for operating what it said were an "illegal" exchange and a "sham" compliance program, while the SEC sued Binance and CEO Changpeng Zhao saying that Binance artificially inflated its trading volumes, diverted customer funds, failed to restrict U.S. customers from its platform and misled investors about its market surveillance controls.

The exchange is also under investigation by the U.S. Justice Department over possible money-laundering and sanctions violations, Reuters had reported in December.