A sticker that reads "Bitcoin accepted here" is displayed at the entrance of the Stadthaus town hall in Zug, Switzerland, August 30, 2016. REUTERS/Arnd Wiegmann

LONDON (Reuters) - Web-based digital currency bitcoin hit its highest levels in almost three years on Friday, extending gains since India sparked a cash shortage by removing high-denomination bank notes from circulation a month ago.

Bitcoin was trading as high as $774 on the New York-based itBit exchange, up almost 1 percent on the day and the highest since February 2014, having climbed almost 9 percent in the past month.

Bitcoin is a cash alternative that can be used for moving money across the globe quickly and anonymously with no need for a central authority to process transactions. It has climbed around 80 percent so far this year, far exceeding its 35 percent rise in 2015.

Indian prime minister Narendra Modi announced a shock move on Nov. 8 to ditch 500 and 1,000 rupee notes - worth a combined $256 billion - that he said were fuelling corruption, being forged and even paying for attacks by militants who target India.

The cryptocurrency’s value has been highly volatile - after rocketing above $1,100 in 2013, it had fallen to around $150 by early 2015. But it has since stabilized, staying above $500 for the past six months.