Apple has moved a step closer to victory in its case against Psystar, after a US judge on Tuesday threw out the Mac clone vendor's anti-trust claim.

Psystar had argued that the Mac OS computer market is separate from the PC market, and that, as such, Apple is maintaining an illegal monopoly by refusing to allow other vendors to sell computers pre-loaded with OS X.

Apple allowed third-party vendors to build computers which ran the Macintosh operating system for a brief period in the 1990s, but the licensing deals were revoked shortly after Steve Jobs returned as chief executive in 1997.

District Judge William Alsup rejected Psystar's claims, ruling that Apple faces competition in the market from other hardware and software vendors, and that suggestions of a monopoly were unfounded. Psystar has until 8 December to appeal the decision.

The original filing was made in response to a copyright infringement suit filed by Apple. Psystar made headlines this summer when it began offering computers built out of PC hardware which would be capable of running OS X, Windows and Linux.

Projects to install OS X on PC hardware exist, but the practice of running the system on a non-Apple computer is expressly forbidden in the Mac OS X terms of service.