Barnes & Noble claims that Microsoft is attempting to stifle competition in the mobile device market and has asked the Department of Justice to investigate, reports Bloomberg.

In a letter to Gene Kimmelman, the DoJ's chief counsel for competition policy, Barnes & Noble argues that by demanding patent royalties for Android devices, "Microsoft is attempting to raise its rivals' costs in order to drive out competition and to deter innovation in mobile devices."

Microsoft sued Barnes & Noble in March, claiming that the company's NOOK and NOOK Color tablets infringe on five Microsoft-held user interface patents. This lawsuit came after the two companies failed to agree on license terms for patents that Microsoft says are infringed upon by Android. While a growing list of Android vendors, including HTC, Samsung, and Amazon, have agreed to license Microsoft's patents, Barnes & Noble refused, claiming that the license would restrict its ability to upgrade the software on its tablets.

The book retailer claims also that the fees Microsoft was demanding were equal to or greater than those it demanded for an entire operating system, Windows Phone, even though the patents covered only "trivial and non-essential design elements" of the Android user interface. It also noted that there is only one patent common to the the five patents it is being sued over and the six that Microsoft was offering to license.

Beyond Microsoft's own patents, Barnes & Noble also raised concerns over deals that Microsoft has entered into with Nokia and MOSAID. In September, MOSAID acquired 2,000 wireless technology patents from Nokia. Instead of paying for these patents, MOSAID announced that it had entered a revenue-sharing scheme with Nokia and Microsoft; two-thirds of any revenue generated by licenses or lawsuits will be given to Microsoft and Nokia.

The letter also draws specific attention to statements made by Nokia CEO Stephen Elop; after announcing the partnership between Nokia and Microsoft, Elop said that the "number one priority is to compete with Android."

Together, these direct and indirect assaults on Android are described by Barnes & Noble as an attempt to defend Microsoft's desktop monopoly from the threat posed by the free Android operating system. The letter states that smartphones and tablets will increasingly replace PCs, diminishing the value of Microsoft's desktop operating system, and that ultimately Android and Chrome will become direct competitors for Windows.

The trial between Barnes & Noble and Microsoft is due to start in February 2012.