Digital music seller Rhapsody is launching a $50 million marketing assault on Apple’s iTunes, offering songs online and via partners including Yahoo Inc and Verizon Wireless, Rhapsody said on Monday.

The songs will be sold in MP3 format, which means users of the Rhapsody service will be able to play them on iPods.

Before now Rhapsody, jointly owned by Real Networks Inc and Viacom Inc’s MTV Networks, had focused on a subscription service, allowing unlimited song streaming for $13 to $15 a month, rather than selling downloads.

But Rhapsody Vice President Neil Smith said the fact the service has not been compatible with Apple Inc’s top-selling iPod digital player has limited Rhapsody’s reach.

“We’re no longer competing with the iPod,” Smith said. “We’re embracing it.”

Rhapsody also will be the music store back-end to MTV’s music Web sites and iLike, one of the most widely used music applications on social networking site Facebook.