IBM has called upon the IT industry to refrain from using patents to challenge Linux and open source.

In an eerie reminder of SCO's litigation alleging that Linux infringes on its copyrights, a study by Open Source Risk Management (OSRM) released on Monday pointed out that the Linux kernel potentially infringes on 283 patents.

The report has come under criticism, partly because OSRM sells insurance policies that indemnify companies against patent claims against Linux, making the conclusions self-serving.

IBM has for years been the largest filer of patents. Together with other Linux backers such as HP and Cisco, IBM owns one third of the patents identified by OSRM.

"I can assure you that IBM has no intention of using its patents against the Linux kernel," IBM's senior vice president for technology and manufacturing, Nick Donofrio, told delegates at LinuxWorld.

"I would challenge the IT community at large to make a similar statement about enforcing their patents."

Although the IBM statement is intended to assure developers, open source advocate Bruce Perens wants additional guarantees that the company will keep its promise.

"I want to know that the Linux and open source developers like myself are safe from IBM's own patents. I would like a signed document to that effect," he said.

Perens, who is on the board of directors of OSRM, said he would keep pushing the subject until IBM ensured that its customers, and the open source developers who work on the products it sells, are not at risk from legal action.

"Which is not something that IBM tells their Linux and open source customers today," he added.