Conan O'BrienLooks like NBC is taking its moratorium on TV appearances by Conan O'Brien pretty seriously. So seriously, in fact, that the network has refused to allow O'Brien to appear on 'American Idol's' charity special, 'Idol Gives Back,' according to the Hollywood Reporter.

The special, which has raised millions for various charities, is set to air on FOX on April 21.

Conan's 'Idol' invite is not related to the ongoing discussions between the network and the comic for his own late-night talk show once NBC's ban is lifted in September. In the meantime, O'Brien will be honing his stand-up skills on a nationwide comedy tour beginning April 12 in Eugene, Oregon. For the full story on Conan's blocked charity gig, visit AOL Inside TV.