REDMOND, Wash., Nov. 6 (AP) — Microsoft said Tuesday that it had fired its chief information officer, Stuart L. Scott, for violations of company policies, but a spokesman declined to give the exact reason for the dismissal.

“Stuart Scott’s employment with Microsoft was terminated after an investigation for violation of company policies,” a Microsoft spokesman, Lou Gellos, said, reading from a company statement.

Mr. Gellos said Mr. Scott was dismissed Friday. He would not elaborate.

According to Microsoft’s Web site, Mr. Scott was responsible for the information technology infrastructure at the company, the world’s largest software maker. He reported to B. Kevin Turner, Microsoft’s chief operating officer, who in turn reports directly to the chief executive, Steven A. Ballmer.

Mr. Scott joined Microsoft in 2005 after 17 years at General Electric, according to Microsoft.

Mr. Gellos said that Alain Crozier, a corporate vice president who also reports to Mr. Turner, and Shahla Aly, a general manager in the services group, would take over Mr. Scott’s duties until a successor is found.