Google's rivals have again prompted antitrust investigators at the Federal Trade Commission to examine the company's business practices, and staff members have begun a preliminary look at whether Google abuses its market dominance in online display advertising such as the banner ads on web pages.
People who have been contacted over the inquiry said the FTC had begun asking questions about Google's practices, specifically whether the company was bundling advertising services in a way that prohibited rivals from competing for the business of advertisers.
The FTC said in December 2007 it would monitor Google's practices in that area. At that time it found that Google's proposed acquisition of DoubleClick, an online advertising company that specialised in display ads, was "unlikely to substantially lessen competition".
Officials at the FTC and Google declined to comment on Friday on the possibility of a new inquiry.
The FTC closed an antitrust investigation of Google's search business less than five months ago, voting unanimously not to proceed with an antitrust case after months of pressure from Google's rivals.
That investigation focused on how Google's search engine presented results of consumer queries, and whether the company purposely gave higher rankings and more prominent display to results that featured its own businesses.