Mark Karpeles, the head of defunct Bitcoin exchange MtGox, manipulated its computer system at least 30 times over a couple of years, a report said Monday, as Tokyo promised greater efforts to regulate the digital currency.

The fresh allegation against France-born Karpeles, 30, follows his arrest Saturday by Tokyo police, more than a year after the once-dominant exchange collapsed in the wake of fraud allegations.

Citing investigators, Japan's top-selling Yomiuri newspaper said Monday that Karpeles fraudulently tinkered with data and transferred funds to other firms controlled by him dozens of times between 2011 and 2013.

Police are questioning Karpeles about his alleged spending of customer deposits worth about 1.1 billion yen ($8.9 million), according to public broadcaster NHK and the Yomiuri.

Officially, Karpeles was arrested for allegedly manipulating data in 2013 to artificially create about $1.0 million in Bitcoins.

But police were also investigating his possible involvement in the massive loss of hundreds of millions of dollars worth of the virtual currency last year, local media have said.

Mark Karpeles, the head of defunct Bitcoin exchange MtGox, manipulated its computer system at least 30 times over a couple of years, a report said Monday, as Tokyo promised greater efforts to regulate the digital currency.

The fresh allegation against France-born Karpeles, 30, follows his arrest Saturday by Tokyo police, more than a year after the once-dominant exchange collapsed in the wake of fraud allegations.

Citing investigators, Japan's top-selling Yomiuri newspaper said Monday that Karpeles fraudulently tinkered with data and transferred funds to other firms controlled by him dozens of times between 2011 and 2013.

Police are questioning Karpeles about his alleged spending of customer deposits worth about 1.1 billion yen ($8.9 million), according to public broadcaster NHK and the Yomiuri.

Officially, Karpeles was arrested for allegedly manipulating data in 2013 to artificially create about $1.0 million in Bitcoins.

But police were also investigating his possible involvement in the massive loss of hundreds of millions of dollars worth of the virtual currency last year, local media have said.