THE cryptocurrency market has lost $US206 billion overnight in what traders are describing as a "cryptocalypse", with bitcoin heading back towards its $US10,000 milestone first reached last November.

But it was smaller currencies including ripple, ethereum and bitcoin cash that were the hardest hit in the latest sell-off, which was sparked by fresh fears of a crackdown on virtual currencies by governments in South Korea and China.

At the time of writing, ripple was down nearly 50 per cent on the previous day, ethereum had lost nearly 34 per cent of its value, bitcoin cash was down nearly 37 per cent and bitcoin was down 27 per cent to just under $US10,200.

The market capitalisation of more than 1300 cryptocurrencies has dropped by around 30 per cent over the past 24 hours, down from $US702 billion to $US496 billion, according to Coinmarketcap.

"It's been a cryptocalypse overnight with bitcoin and other virtual currencies coming under heavy selling pressure as the regulatory scrutiny intensifies not only in China and South Korea but across the globe," Greg McKenna, chief market strategist at AxiTrader, said in a note on Wednesday. "The debate over zero or $US100,000 for bitcoin this year continues, however."