A US judge yesterday threw out a copyright lawsuit filed against YouTube by US entertainment giant Viacom, handing the Google-owned video site a major legal victory in a closely watched case.

US District Court Judge Louis Stanton said in his 30-page ruling that YouTube was protected against Viacom's claims of 'massive copyright infringement' by provisions of the Digital Millennium Copyright Act.

The 1998 legislation provides protection for Internet firms from copyright violations by their users, and the judge ruled that YouTube's actions, such as quickly removing infringing videos when requested, were in line with the act.

Google welcomed the ruling, while Viacom vowed to appeal.

'This is 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,' Google general counsel Kent Walker said.

'The decision follows established judicial consensus that online services like YouTube are protected when they work cooperatively with copyright holders to help them manage their rights online,' he added.

Viacom general counsel Michael Fricklas said the company was 'disappointed with the judge's ruling, but confident we will win on appeal'.

'Copyright protection is essential to the survival of creative industries. It is and should be illegal for companies to build their businesses with creative material they have stolen from others,' he said.

US movie and television giant Viacom had sued Google and YouTube for $1 billion in March 2007, arguing that they condoned pirated video clips at 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 also routinely posted on YouTube without authorisation.

Viacom's suit charged that YouTube was a willing accomplice to 'massive copyright infringement' and sought more than $1 billion in damages.

Viacom's film and television empire includes many youth-oriented networks like MTV and VH1, popular comedy shows such as 'The Daily Show' and the Paramount movie studio.

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