Japanese prosecutors on Friday charged the head of collapsed Bitcoin exchange MtGox with embezzlement, Jiji Press news agency said, amid fraud allegations over the disappearance of hundreds of millions of dollars worth of the virtual currency.

The charges, which could not be immediately confirmed, come after France-born Mark Karpeles, 30, was taken into police custody in Tokyo last month over the affair. It was unclear if the indictment related to all or a part of the missing money.

He has been held without formal charge for six weeks, as allowed under Japanese law.

Karpeles was first taken into custody over claims he fraudulently tinkered with data and transferred funds to other firms controlled by him dozens of times between 2011 and 2013.

He was later rearrested for allegedly pocketing about 321 million yen ($2.7 million) worth of Bitcoin deposits, extending an initial three-week incarceration during which time police likely grilled him over the incident.

Tokyo-based MtGox froze withdrawals in early 2014 and was later shuttered over the missing money, which it said was linked to a bug in the software underpinning Bitcoins that allowed hackers to pilfer them