China’s largest bitcoin producing provinces have intensified a crackdown on cryptocurrency mining in the latest sign of how global authorities are toughening their stance on the rapidly growing digital asset markets.

The country’s bitcoin mining operations, the power-hungry process of computational puzzle-solving that creates new units of the virtual currency, have been in retreat since May when the government confirmed a ban on cryptocurrency transactions and warned of the risks of using them for payments. Bitcoin prices plunged after the announcement and are currently trading at about $30,000 below the April peak of almost $65,000.

China’s latest intervention places further pressure on what was once one of the world’s most vibrant markets for trading and mining digital currencies. It comes at a time when many governments are scrutinising the industry’s affect on the environment and determining the types of financial oversight that should be applied to cryptocurrencies.