The Initiative for Software Choice, which counts Microsoft, Cisco Systems and Intel among its backers, said in comments filed Tuesday that the department should "avoid crafting needless and potentially detrimental IT policy to promote the use" of open-source software. "Open source" means every software developer can view the source code for software, modify it, and use it for free.

The initiative, which launched in May and is chaired by a group called CompTIA, an organization that has close ties to Microsoft, is worried about a recent report that concluded the Defense Department relies on open-source software and recommended its further adoption.

Written by defense contractor MITRE, the report said that free and open-source software "plays a more critical role in the (Defense Department) than has been generally recognized" and endorsed it as a viable alternative to proprietary Microsoft products.

This week, the Initiative for Software Choice counterattacked, telling the Defense Information Systems Agency that the Pentagon should not "openly promote the use" of open-source software, arguing that proprietary products are not inherently less secure.

The group also assailed the General Public License (GPL), which generally permits programmers to incorporate code released under the GPL as long as they make their own source code available.

"While the law on this matter remains untested, it makes sense for companies to be highly risk-averse in this area, striking a more defensive posture when confronted with software development that may implicate GPL code or similar coding environments," the initiative said. "Commercial and hybrid software developers generally do not want to risk losing their investment."

Proprietary software companies such as Microsoft have labeled open-source software as a serious threat and have begun to oppose its use by governments. At the same time, however, nations such as France and Germany have begun to encourage open-source software to limit their dependence on proprietary vendors and to stimulate local software development.