Microsoft is set to strengthen intellectual property protection for manufacturers and distributors using its software. The move comes in an attempt to stem apprehension about patents.

The company has removed a cap on some legal costs for companies that use or alter source code in Windows Embedded and Windows Mobile software platforms. Costs covered by the move would include patent, copyright, trademark and trade secret claims.

Microsoft said about 4,000 companies use embedded or mobile software. The company did not reveal the previous limit.

"We want our partners to have confidence they are not unnecessarily exposing themselves to IP problems," said Hardy Poppinga, Microsoft spokesman. "We're only making money if our partners are making money."

Microsoft introduced the IP programme in 2003, Poppinga said. It was expanded in 2004 to cover low-volume customers and partners, he added.

The changes bring those who use the Embedded and Mobile software in their devices in line with the patent protection Microsoft has extended to some of its other flagship products.

Microsoft's Embedded and Mobile software is used in smartphones, portable media centers, ATM machines, retail point-of-sale systems, industrial robots and thin clients.

In December, Visto accused Microsoft of a "blatant" infringement on three U.S. patents related to accessing e-mail from phones and other wireless devices. Visto filed suit in U.S. District Court in Texas seeking unspecified monetary damages and an injunction to stop Microsoft from shipping its Windows Mobile 5.0 platform, released in May 2005.

The timing of the new program with that litigation is "purely coincidental," Poppinga said. "The Visto case has nothing to do with what we're announcing here," he said.

Microsoft is currently involved in 35 patent-infringement disputes, according to a filing last month with the US Securities and Exchange Commission. Poppinga said he did not have information on any cases that deal with Windows Embedded or Windows Mobile software.

Also closely watched is NTP's patent-infringement case against RIM, the vendor providing the popular BlackBerry push e-mail service. NTP is seeking a permanent injunction that would cause a BlackBerry blackout.