“There’s no fixed definition on whether it’s a currency or not. This issue is a difficult one,” Aso said after a cabinet meeting.
“It has not yet been proven to be credible enough to become a currency, so I need to watch for a little while more.”
He added virtual currencies may be widely used in countries such as China but that they were less common in Japan, where hard currency is still preferred.
Bitcoin’s prices have risen more than 1,700 percent since the start of the year, triggering worries about a bubble.
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