Some estimates put the global market for Bitcoins, a virtual currency created, or 'mined' through complicated computer algorithms, at about $7bn (£4.2bn).

Countries and their tax authorities have been grappling with how to regulate it, with some seeing it as a route for tax evasion or money laundering.

Russia has declared transactions illegal, China has banned its banks from handling Bitcoin trades, and there have been calls for the US to do the same.

Singapore has imposed a tax on Bitcoin trading and using it to pay for services, after classifying it as goods, rather than a currency.

Last month leading Bitcoin exchange, Tokyo-based MtGox, filed for bankruptcy after losing an estimated 750,000 of its customers' Bitcoins.