US antitrust regulators may investigate Google's dominance of the Web search industry, a source told Reuters Tuesday. The Federal Trade Commission and Justice Department will decide which has more expertise and whether to launch a formal investigation once scrutiny into the Google's plan to buy ITA Software is done. The Internet giant has been under investigation by the European Commission since last November. There have been a series of complaints made to regulators, many from Google rivals which specialize in vertical searches. Several of these have complained to US and European antitrust authorities that Google is seeking to hurt their business by making them hard to find in Google searches, said Gary Reback, who represents some of these companies.