The Ministry of Public Security said that Police in China arrested over 1,100 people suspected of using cryptocurrencies to launder illegal proceeds from telephone and Internet scams in a recent crackdown.

The arrests came as authorities in China step up their crackdown on cryptocurrency trading.

Last month, three industry bodies banned crypto-related financial and payment services, and the State Council, China’s cabinet, vowed to clamp down on bitcoin mining and trading.

The public security ministry said that by Wednesday afternoon police had busted more than 170 criminal groups involved in using cryptocurrencies to launder money.

The money launderers charged their criminal clients a commission of 1.5% to 5% to convert illegal proceeds into virtual currencies via crypto exchanges, the ministry said via its official Wechat account.

China’s Payment & Clearing Association said on Wednesday that the number of crimes involving the use of virtual currencies is on the rise.