The South Korean government on Thursday said 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.

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