Microsoft on Sunday confirmed reports that it reportedly believes open-source software users owe the company royalties on 235 alleged patent violations.

In an interview with Fortune magazine, Brad Smith, Microsoft's general counsel, and Horacio Gutierrez, the company's vice president of intellectual property and licensing, said open-souce software, including Linux, violates 235 Microsoft patents. And Microsoft wants distributors and users of open-souce software to start paying royalties for these alleged violations.

"This is not a case of some accidental, unknowing infringement. ...There is an overwhelming number of patents being infringed," Gutierrez said.

Microsoft executives were not immediately available to comment on the article.

However, according to in an e-mail received by Computerworld late Sunday night, a Microsoft spokesman said the company was motivated to speak over concerns that the latest draft of the General Public License version 3, which governs distribution and use of Linux and many other open-source software, "attempts to tear down the bridge between proprietary and open source technology that Microsoft has worked to build with the industry and customers."

"The Free Software Foundation's efforts with GPLv3 while not harming existing contracts can harm the desired interoperability and open exchange that we have increasingly seen between proprietary and open source over the past several years," he wrote.

The spokesman pointed out that a free software group called the Open Source Risk Management Group itself had confirmed via an August 2004 study (PDF format) that Linux could be in violation of 283 patents, though none of those patents had been proven in court at the time.

He also said that Microsoft's "longstanding preference is to license rather than litigate and Microsoft's work over the past three years to build a bridge with open source is a result of that commitment."

Smith broke down the alleged patent violations during the Fortune interview, saying the Linux kernel violates 42 patents and the operating system's user interface violates a further 65. He went on to claim that the Open Office application suite violates 45 patents and open-source e-mail applications infringe on 15 more. Other open-source software applications infringe on 68 patents, Smith said.

Microsoft has been laying the groundwork for patent claims against Linux and open-source software for some time. Most notably, the Redmond, Washington, software company signed a Linux deal with Novell Inc. that indemnifies the company against Microsoft patent claims over Linux. Last week, Dell joined the deal, becoming the first hardware vendor to do so.

Microsoft has struck other deals with hardware makers. In April, Samsung Electronics Co. and Microsoft signed a cross-licensing agreement that included a clause that indemnified Samsung against Linux patent claims.