Italian media company Mediaset is suing Google, owners of YouTube, for copyright infringement.

Mediaset, which is controlled by Italian prime minister Silvio Berlusconi, claims that an analysis of YouTube videos last month found 4,643 Mediaset video clips amounting to more than 325 hours of material.

The company estimates that it has lost 315,672 viewing days and is claiming for the costs of broadcast. The figure does not include lost advertising revenue.

This latest legal challenge is making YouTube a very expensive purchase for Google. A $1bn legal case from Viacom also hangs over the company.

"There is no need for legal action. We prohibit users from uploading infringing material and we cooperate with all copyright holders to identify and remove infringing content as soon as we are officially notified," Google said in a statement.