Opera Software, a smaller competitor in the web browser business, asked European Commission regulators on Thursday to investigate the possibility of anti-competitive conduct by Microsoft Corp over the inclusion of the Internet Explorer browser with the Windows operating system.

Opera wants EU regulators to require Microsoft not to include Internet Explorer in Windows or to possibly reinstall other browsers on the computer.

Previous antitrust legal settlements have required Microsoft to allow any PC maker to pre-install any other browser into the systems. It has not required the removal of Internet Explorer.

The EU has received the complaint and must now decide how to act on it.