Cryptocurrency exchanges are racing to sever ties with customers in mainland China. The move comes after Beijing signalled last week that it was cracking down on e-coin trading. Ten powerful Chinese regulators said that overseas exchanges would now be barred from providing services to mainland customers via the internet. That was previously a grey area in the rules. On Monday (September 27) major platforms Binance and Huobi Global stopped registering new users in the country. Huobi also pledged to clean up existing accounts by the end of the year. But that didn't stop shares in affiliate Huobi Tech plunging by more than a fifth. Crypto firms around the world face increased scrutiny, but outright bans are rare. However, authorities in China have come to see bitcoin and the like as volatile, speculative assets of no intrinsic value. They also see them as a way to get around the country's capital controls. Following crackdowns on big tech firms and other sectors, it looks like Beijing watchdogs now have crypto in their sights.