Mediaset SpA, the television company controlled by Italian Prime Minister Silvio Berlusconi, sued the YouTube video-sharing Web site and its owner Google Inc. on Wednesday, seeking ''at least'' €500 million ($779 million) in damages. The Italian company accused YouTube of distributing and exploiting its commercial property.

Mediaset joins a series of leading broadcasters to have sought compensation from YouTube, a video-sharing website, for alleged copyright infringement.

Gestevision Telecinco SA, a Mediaset unit that owns Spain's most-watched TV station, sued YouTube last month for copyright infringement and illegally posting its video content on the Web. In a separate suit, France's largest commercial broadcaster TF1 TFFP.P asked for damages of €100 million for a similar reason.

YouTube is also facing a $1 billion copyright infringement suit from American media conglomerate Viacom Inc. that accuses it of profiting from clips from Viacom shows illegally uploaded by YouTube users.(See: Google ordered to release YouTube user data to Viacom in $1-billion lawsuit)

Mediaset alleges that it found at least 4,643 copies of its programming on YouTube on 10 June, when it conducted a sample survey. That programming represents approximately 325 hours of material, Mediaset claims.

The media company, as a result, alleges that its three Italian television networks have lost nearly 315,700 viewer days, which, in turn, represents lost advertising opportunities for its television programs, Mediaset alleges.

The claim of €500 million corresponds to ''immediate damages,'' Mediaset said in a statement. Lost advertising revenue linked to the videos may add to the amount of compensation demanded, Mediaset said.

''YouTube respects copyright holders and takes copyright issues very seriously,'' YouTube said in an e-mailed response. ''There is no need for legal action and all the associated costs. We prohibit users from uploading infringing material, and we cooperate with all copyright holders to identify and promptly remove infringing content as soon as we are officially notified.''

YouTube is a video sharing website where users can upload, view and share video clips. Three former PayPal employees - Chad Hurley, Steve Chen and Jawed Karim, created YouTube in mid-February 2005.

The San Bruno-based service uses Adobe Flash technology to display a wide variety of user-generated video content, including movie clips, TV clips and music videos, as well as amateur content such as video-blogging and short original videos.

In October 2006, Google Inc. announced that it had reached a deal to acquire the company for $1.65 billion in Google stock. The deal closed on 13 November 2006.