Google's new search feature called Google Search Plus has garnered a lot of attention since its recent launch with critics like Twitter slamming the search giant for favoritism towards Google's social network. The new search feature is now being investigated by the U.S. Federal Trade Commission, according to a source inside the U.S. regulatory body.

Google Search Plus World is a new feature that tailors Google search results to individual users by adding results from Google's own social network, Google+. Typing in a search query about "football" for instance would generate results from Google+ posts and photos. Twitter and other tech sites have criticized the new feature as it unfairly promotes Google own social network over other sites like Facebook or Twitter.

According to the Bloomberg source, the FTC is expanding its ongoing antitrust probe to look into this new feature if Google is manipulating the search results to increase traffic to its social network. Competing companies have complained that Google is using its search market clout to shut out results from other social networks. The new feature doesn't use results from much larger and established social networks like Facebook or Twitter.

Google has said that the Search Plus Your World will benefit users and that it has no legal duty to promote its rivals services.

"The laws are designed to help consumers benefit from innovation, not to help competitors," said Adam Koracevich, a Google spokesman. "We believe that our improvements to search will benefit consumers by better surfacing social content, and the great thing about the openness of the Internet is that if users don't like our service, they can easily switch to another site."

The point in the antitrust case is that Google is shutting out competition simply because it can. Companies who want to get good search results will have to join Google+. Google's locking out of Facebook and Twitter is among the potential violations that the FTC is investigating.