TOKYO (AP) — A bitcoin mining company within Slovenia has been hacked for the probable theft of tens of millions of dollars, simply days before the virtual currency, which usually hit a record above $15, 500 on Thursday, is due to start investing on major U. S. trades.

NiceHash, a company that mines bitcoins on behalf of customers, said it is checking out a security breach and will stop working for 24 hours while it verifies how many bitcoins were taken.

Research company Coindesk said that a wallet address known by NiceHash users indicates that will about 4, 700 bitcoins have been stolen. At Thursday’s record associated with about $15, 000, that places the value at over $70 mil.

There was no immediate response through NiceHash to an emailed request for additional information.

“The incident has been reported towards the relevant authorities and law enforcement and are cooperating with them as an issue of urgency, ” it mentioned. The statement urged users to improve their online passwords.

Slovenian law enforcement are investigating the case together with regulators in other states, spokesman Bostjan Lindav said, without providing details.

The particular hack will put a limelight on the security of bitcoin just like the trading community prepares for your currency to start trading on 2 established U. S. exchanges. Futures for bitcoin will start trading at the Chicago Board Options Exchange upon Sunday evening and on crosstown competitor CME Group’s platforms later within the month.

That has increased the feeling among some investors that bitcoin is gaining in mainstream legitimacy after several countries, like China and taiwan, tried to stifle the virtual foreign currency.

As a result, the price of bitcoin has leaped in the past year, particularly so within recent weeks. On Thursday this surged to over $15, 000, upward $1, 300 in less than a day, based on Coindesk. At the start of the year, one particular bitcoin was worth less than $1, 000.

Bitcoin is the world’s most widely used virtual currency. Such currencies aren’t tied to a bank or federal government and allow users to spend money anonymously. They are basically lines of personal computer code that are digitally signed every time they are traded.

A debate is definitely raging on the merits of this kind of currencies. Some say they function merely to facilitate money washing and illicit, anonymous payments. Other people say they can be helpful methods of transaction, such as in crisis situations exactly where national currencies have collapsed.

Miners of bitcoins and other virtual foreign currencies help keep the systems honest with their computers keep a global operating tally of transactions. That stops cheaters from spending the same electronic coin twice.

Online security is really a vital concern for such negotiations.

In Japan, following the failure of the bitcoin exchange called Mt. Gox, new laws were enacted to manage bitcoin and other virtual currencies. Mt. Gox shut down in February 2014, saying it lost about 850, 000 bitcoins, possibly to cyber criminals.

Ali Zerdin in Ljubljana, Slovenia, and Carlo Piovano working in london contributed to this story.