San Francisco - Apple has sued a small computer-maker for selling Intel-based computers that are pre-installed with the Apple operating system, The Wall Street Journal reported Tuesday.

Psystar Corp began offering the Mac clones in late April for around 600 dollars, a significant discount compared to Apple-branded machines. Psystar's devices run on the same Intel processors used by Apple but violated the company's software licence agreement, which limits installation of the Mac operating systems to Apple hardware.

The copyright infringement lawsuit against Miami-based Psystar was filed in the US District Court for the Northern District of California, alleging violations of copyright and software licensing agreements.

The 16-page complaint alleges that Psystar committed copyright infringement, breach of contract, trademark infringement and unfair competition.

The complaint alleges that Psystar offered updates through its Web site of Apple's Leopard operating system that "are either direct copies of Apple-generated updates and/or unauthorized modified versions of software updates from Apple." (dpa)