Siri foreign language question

As a iPhone 4 user I have only used Siri briefly on friend's 4Ss. My wife and I will upgrade to the iPhone 5 (the new iPhone etc.) this fall and plan to upgrade my parents too. My father is a native italian speaker and I was wondering if you could use Siri with a foreign language interchangbly with English and if not can you set Siri for the foreign language but the phone UI for English? I know my father wouldn't want the main phone set to italian but would love to speak to Siri in Italian perhaps mixed with occasional English when not around family.

Thanks!