Regulators in Asia Pacific have become increasingly uneasy with the rise of cryptocurrencies such as bitcoin.
The latest to sound a warning was the Bank of Japan Governor Haruhiko Kuroda, who called the surge in bitcoin prices "abnormal" at a media conference on Thursday. His comments echoed warnings made by his counterparts in major economies in the region, including Australia, South Korea and Singapore.
Their worries are not unfounded as Asia accounts for the bulk of trading in bitcoin, the largest cryptocurrency by value.
At the end of November, Japan, South Korea and Vietnam contributed 80 percent of bitcoin trading activity globally, the Wall Street Journal reported, citing data from research firm CryptoCompare.