The world's biggest recording companies have been stripped of two billion YouTube hits after the website cracked down on alleged 'fake viewers'. Universal, home of Rihanna, Nicki Minaj and Justin Bieber, lost a total of one billion views in the video site's biggest ever crackdown on artificially inflated figures. Sony was second hardest hit, with the label behind such stars as Alicia Keys, Rita Ora and Labrinth losing more than 850million views in a single day. The dramatic cuts came as YouTube conducted a crackdown on fake views, but music industry sources have blamed it on housekeeping related to the migration of their videos across different channels. The unprecedented move left Universal with just five videos on the site - none of which were music - and Sony with just three. 'This was not a bug or a security breach. This was an enforcement of our viewcount policy,' YouTube announced. It marks a huge commercial blow to all the artists involved as YouTube is now the web's most important outlet for music videos Over four billion hours of video are watched by over 800million unique visitors to the site each month. The dramatic falls, highlighted by figures compiled by YouTube statistics analysts at SocialBlade, came after YouTube conducted an audit of its viewing figures aimed at combating 'black hat' view count-building techniques. That is the term used when hackers artificially build up the numbers of views or likes on a YouTube video - enabling them to make clips appear far more popular than they really are and increase their exposure on the site. The number of views attracted on YouTube are these days regarded as an unofficial worldwide popular music chart, so once it became clear that hits had been inflated, fingers immediately pointed at the record industry.