Psystar's counter-claims against Apple - their defense for making Mac clone computers - have been dismissed by a California judge.

Psystar had argued that Apple violated antitrust laws through its attempts to block third parties from selling rival Mac OS X-based computers, but Apple's motion to get this dismissed has been granted.

Apple sued Psystar in July, as the Florida-based firm was violating its copyright and trademarks by selling computers running a hacked version of the Mac OS X operating system without authorisation.

"Apple asks its customers to purchase Mac OS knowing that it is to be used only with Apple computers", Judge Alsup wrote. "It is certainly entitled to do so."

"The counterclaim admits that market studies indicate that, although Apple computers with Mac OS enjoy strong brand recognition and loyalty, they are not wholly lacking in competition."

Psystar has until 8 December to better its argument through an amended complaint.