SANTA CLARA, Calif. - Microsoft CEO Steve Ballmer intends to keep the regulatory heat on Google as his company strives to lessen its rival's dominance of Internet search.

In an appearance Tuesday at a search engine conference in Santa Clara, Ballmer said Microsoft believes Google has done a number of things to gain an unfair advantage in the Internet's lucrative search advertising market. He didn't specify the alleged misconduct.

Microsoft already has helped convince U.S. regulators that Google would break antitrust laws in two proposed deals: a search advertising partnership with Yahoo that was scrapped in 2008 and a digital books settlement that still needs court approval.

Ciao, a website owned by Microsoft, also has filed an antitrust complaint against Google in Europe.