South Korea’s government said on Thursday it plans to ban cryptocurrency trading, sending bitcoin prices plummeting and throwing the virtual coin market into turmoil as the nation’s police and tax authorities raided local exchanges on alleged tax evasion.

The clampdown in South Korea, a crucial source of global demand for cryptocurrency, came as policymakers around the world struggled to regulate an asset whose value has skyrocketed over the last year.

There are more than a dozen cryptocurrency exchanges in South Korea, according to Korea Blockchain Industry Association.

The proliferation of the virtual currency and the accompanying trading frenzy have raised eyebrows among regulators globally, though many central banks have refrained from supervising cryptocurrencies themselves.

Justice minister Park Sang-ki said the government was preparing a bill to ban trading of the virtual currency on domestic exchanges.

Read more in Reuters.