Washington ? Linux software has been approved for use on the most sensitive computers in corporations and the federal government, including those inside banks and the Pentagon, an important step for software widely considered the top rival to Microsoft Corp.

The Common Criteria organization, an international technology standards body, certified Linux for the first time on “mission critical” computers, including those in America’s top-secret spy agencies and those used to deliver ammunition, food and fuel to soldiers. The certification is akin to the technology industry’s seal of approval.

Supporters said it could increasingly help persuade skeptical governments and corporations to consider Linux, created and developed collectively by an international community of programmers, as an alternative to Microsoft’s flagship Windows software.

Linux was certified as providing only “low to moderate” security, compared with the same group’s certification as “moderate to high” last year of the security of Microsoft’s Windows 2000 software.

The approval, announced Wednesday, involves only one version of Linux, from SuSE Linux AG, a vendor based in Nuremberg, Germany.