Viacom has demanded that YouTube site remove all Viacom content from its site.

Viacom includes BET, Famous Music, MTV Networks - MTV, VH1, Nickelodeon, Nick at Nite, Comedy Central, CMT: Country Music Television, Spike TV, TV Land Paramount Pictures and Paramount Home Entertainment - a cornucopia of YouTube-traffic-generating content. The company says that content represents about 100,000 video clips - lifeblood to YouTube

Viacom said its pirated programmes on YouTube generate about 1.2 billion video streams, based on a study from an outside consultant, according to a Reuters report.

Viacom's action is one of Google's worst fears realised. YouTube agreed to be acquired by Google last year in a $1.65bn stock transaction. At the time analysts speculated YouTube's ability to avoid lawsuits over the vast amount of copyright material that exists on the site, and some predicted the company would soon be hit with lawsuits. In recent months Universal Music, Sony BMG and Warner Music each signed deals to display their content on YouTube, which could help shield the video site from some lawsuits.

Just last week, YouTube received a subpoena from News Corp's Fox television unit seeking information regarding videos of television programmes - including 'The Simpsons' - that appear on YouTube.

The site has in the past cooperated with some content providers demanding content be removed. For example, it recently deleted close to 30,000 files after complaints from an organisation representing Japanese copyright holders.