Apple’s chief executive Steve Jobs, who is currently on medical leave since late January, will have to answer questions relating to an antitrust lawsuit accusing the firm of creating a monopoly in the field of music-downloading, a federal judge ruled.

U. S. Magistrate Judge Howard Lloyd in San Jose on Monday allowed lawyers for the petitioners in the antitrust lawsuit to question Mr. Jobs for a maximum of two hours.

The judge ruled, “The court finds that Jobs has unique, non-repetitive, firsthand knowledge about the issues at the center of the dispute over RealNetworks software.”

The judge added that the lawyers could question Mr. Jobs only about changes Apple made in its software in October 2004 that thwarted iTunes rival firm RealNetworks’ music files’ chances to be played on Apple’s iPod music players.

Thomas Slattery, an Apple iTunes customer, sued the company in 2005 on behalf of consumers claiming that the company unlawfully restricted consumer choice by linking its musical device, the iPod, to its iTunes music store.

Apple has engaged in several lawsuits regarding its mobile devices, operating software and even its “App Store” trademark.