US entertainment giant Viacom asked an appeals court Friday to overturn a judge's June decision to toss out its billion-dollar copyright lawsuit against YouTube.

Viacom attorneys argued in a filing that US District Court Judge Louis Stanton was wrong to rule that YouTube was protected by provisions of the Digital Millennium Copyright Act (DCMA).

Google general counsel Kent Walker declared Stanton's ruling "an important victory not just for us, but also for the billions of people around the world who use the Web to communicate and share experiences with each other."

But in its appeal, Viacom contended that Stanton should have declared it the winner in the suit because Google had the right and ability to curb "rampant" posting of copyrighted videos and benefited from not doing so.

The US movie and television giant sued Google and YouTube for a billion dollars in March 2007, arguing that they condoned pirated video clips on the website to boost its popularity.

The lawsuit was merged with a similar complaint being pursued by the English Premier League, which said football clips were routinely posted on YouTube without authorization.

YouTube took shelter in DCMA wording that protects websites from being responsible for copyrighted material that visitors post as long as the material is removed when owners point out violations.

Viacom argued in its appeal that the DCMA protection was for "innocent" Internet firms and vanishes "the moment the service provider loses its innocence."

Viacom's suit charged that YouTube was a willing accomplice to "massive copyright infringement" and sought more than a billion dollars in damages.

Viacom's film and television empire includes many youth-oriented networks like MTV and VH1 along with the Paramount and DreamWorks movie studios.

YouTube was a year-old Internet sensation when Google bought it in a 1.65-billion-dollar stock deal in 2006.