Bitcoin blasted to another all-time high of just over $17,750 on Friday, up 8 percent on the day, as concerns grew over the risks of investing in the highly volatile and speculative instrument.
The cryptocurrency's staggering price rises - more than 1,700 percent since the start of the year - have driven worries that the market is a bubble that could burst in spectacular fashion.
Bitcoin has climbed more than 77 % so far in December alone, putting it on track for its best month in percentage terms since December 2013.
On Friday it reached as high as $17,752.99 on the Luxembourg-based Bitstamp exchange.
