Former Canwest Global Communications senior exec Zev Shalev has left his post as the New York City-based executive producer of CBS’ The Early Show to launch an online venture.

Shalev, who took up the CBS post in March 2008, is to launch NewsTsar, a start-up that marries news content with Twitter, Facebook and other social media.

‘Zev tells me that his first project, NewsTsar, brings together news and social media and will launch in the second quarter of next year,’ CBS News and Sports president Sean McManus said in an internal memo Thursday.

NewsTsar will return Shalev to his Internet roots as executive producer of U8TV: The Lofters, an online reality TV show he ran for two years to 2002 for then Alliance Atlantis Communications.

He next moved to broadcast exec posts at Toronto One and CanWest Media, where he was vice president of strategic programming and senior executive producer of information and entertainment programming.