Exclusive third-party downloadable content is a growing trend on Xbox 360.

The upcoming Tomb Raider: Underworld will be the latest title offering Xbox 360 exclusive DLC after it launches, co-publisher Eidos said Monday.

Eidos will offer two packs for download, titled Tomb Raider: Underworld – Beneath the Ashes and Tomb Raider: Underworld - Lara’s Shadow.

Beneath the Ashes is set after the events of original Tomb Raider: Underworld and will be available on Xbox Live Marketplace this Christmas, featuring a new environment an new enemies.

Tomb Raider: Underworld – Lara’s Shadow will launch in "early 2009," and will sport "a new kind of playable character."

The announcement of Tomb Raider DLC follows the announcements of high-profile Xbox 360 exclusive content for Grand Theft Auto IV and Fallout 3, leaving PS3 owners without the option to buy additional content to stretch the life of the games.

The Crystal Dynamic-developed Tomb Raider: Underworld is slated for release in November.