FILE PHOTO: Virtual currency Bitcoin tokens are seen in this illustration picture, December 8, 2017. Picture taken December 8. REUTERS/Dado Ruvic/Illustration/File Photo

TOKYO (Reuters) - Japanese Finance Minister Taro Aso said on Tuesday that bitcoin has not been proven to be a credible currency and that he would watch its developments in the near-term.

He made the remark to reporters when asked about his French counterpart’s comment this week that France would propose a discussion on regulating the virtual currency at a meeting of G20 group of major economies next year.

“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.