SAN FRANCISCO — Google Inc. is joining forces with European regulators in an attack on Microsoft Corp.'s dominance of the Web browser market, injecting more bad blood between two of computing's most powerful companies.
The latest assault on Microsoft's Internet Explorer, announced Tuesday, comes as Google is trying to expand the use of its own Web browser, the 6-month-old Chrome.
A complaint by Opera Software, maker of another Explorer rival, prompted the European Commission to open an investigation into whether Microsoft's bundling of its Web browser with the Windows operating system had stifled competition and innovation.
In their preliminary findings, the European regulators concluded that Microsoft had indeed given its Web browser an unfair advantage that has been in violation of European law since 1996.
Microsoft has until late March to respond, which could force the Redmond, Wash., software maker to detach Internet Explorer from Windows.