Greenwald, who is based in Brazil and was among the first to report information provided by one-time U.S. National Security Agency (NSA) contractor Edward Snowden, wrote in a blog post on Tuesday that he was presented with a "once-in-a-career dream journalistic opportunity" that he could not pass up. 

He did not reveal any specifics of the new media venture but said details would be announced soon. Greenwald did not immediately respond to a request for comment.

  Two sources familiar with the new venture said the financial backer was Omidyar. It was not immediately clear if he was the only backer or if there were other partners. 

Omidyar could not immediately be reached for comment.

  Omidyar, who is chairman of the board at eBay Inc but is not involved in day-to-day operations at the company, has numerous philanthropic, business and political interests, mainly through an investment entity called the Omidyar Network.