Bitcoin broke through the $10,000 barrier for the first time on Wednesday as it extends a stratospheric rise that has delighted investors but sparked fears of a bubble.

The virtual currency hit a high of $10,903 in Asia, according to Bloomberg News, about 14 times its value at the start of the year.

The breakthrough is the latest in a spectacular run for the online money dubbed "digital gold" by its advocates, which began life in 2009 as a bit of encrypted software supposedly written by an unknown coder with a Japanese-sounding name.

Bitcoin, which was valued at just a few US cents when it was launched, has no legal exchange rate, no central bank backing it and is traded on specialist platforms.