EU competition chief Joaquin Almunia told the European parliament Tuesday that Google's battle may be bigger and more complex than the antitrust case Microsoft fought in its heyday.

Google has been investigated in Europe for four years against charges that it rigs search results to its own advantage. Microsoft's case lasted 16 years.

There are a total of 20 formal complaints against Google. Google has made three previous proposals to settle the case, but the EU has rejected each one.

The European Commission asked Google to change its offer for an unprecedented fourth time. Google says it continues to work with the commission to resolve its concerns.

It's unclear when the case will be resolved, and that's one of the dangers that for the European regulators said John Simons, media and technology editor at The Associated Press. "They need to be cognizant of the idea that this could turn into and have the appearance of kind of a witch hunt," he said.