Coincheck, a major cryptocurrency trading exchange in Tokyo, has been hacked into and has lost about 58 billion yen ($534 million) worth of virtual money, national broadcaster NHK reported on Friday.
Coincheck posted on its website on Friday afternoon that it had suspended withdrawals of almost all cryptocurrencies.
The exchange has already reported the incident to the police and to Japan's Financial Services Agency, NHK said.
In 2014, Tokyo-based Mt. Gox, which once handled 80 percent of the world's bitcoin trades, filed for bankruptcy after losing some 850,000 bitcoins - then worth around half a billion U.S. dollars - and $28 million in cash from its bank accounts.