UPDATE 1-Liberty Media posts revenue drop at key unit

* Liberty Interactive rev down 1 percent to $1.9 billion

* Liberty Entertainment, Liberty Capital rev increases

* Shares rise in pre-market trade

NEW YORK, Aug 7 (Reuters) - Liberty Media Corp on Friday reported lower second-quarter revenue at its largest division, Liberty Interactive, with the tough retail environment hurting sales at its QVC shopping channel.

The media conglomerate, controlled by cable pioneer John Malone, said that while revenue declined at Liberty Interactive (LINTA.O), it increased at both Liberty Entertainment LMDIA.O and Liberty Captial LCAPA.O.

At Liberty Interactive, a key division that includes QVC, revenue fell 1 percent to $1.9 billion. Liberty Entertainment, which includes Starz Entertainment, said revenue rise 2 percent to $367 million. Liberty Capital reported a 14 percent increase in revenue to $199 million.

Liberty Media operates under these three tracking stocks to allow investors to more closely follow the assets that are attributed to each stock. (Reporting by Paul Thomasch; Editing by Steve Orlofsky)