The European Commission has started looking into potential antitrust issues related to the way Google handles advertisements included in its Internet search engine results. So far, the European Commission is only looking into complaints it has received, but could launch a formal investigation if the initial research turns over compelling information.

The complaints the Commission is looking into came from Microsoft's Ciao! from Bing product search service, the U.K.-based Foundem price comparison Web site, and ejustice.fr legal search engine in France. Foundem is also part of the ICOMP organization that's funded in part by Microsoft.

The complaints allege that Google is intentionally lowering the rankings of potential competitors. In the case of Ciao! from Bing, the complaints started after the online service was purchased by Microsoft. Prior to finding itself under Microsoft's wing, Ciao! was a Google AdSense partner.

Google maintains that it isn't manipulating where potential competitors land in search results, and that rankings aren't an exact science.

"We are also the first to admit that our search is not perfect, but it's a very hard computer science problem to crack," said Julia Holtz, Google's Senior Competition Counsel. "Imagine having to rank the 272 million possible results for a popular query like the iPod on a 14 by 12 screen computer screen in just a few milliseconds. It's a challenge we face millions of times each day."

The European Commission isn't saying if, or when, it plans to move from an informal review into a formal investigation.